//! The Flow tab (hub spec §13.2): runs of a repository, and a run's job
//! graph with live status and logs.

use super::settings::{csrf, require};
use super::{filters, lookup, lookup_role, Error, Page, RepoShell, Shell};
use crate::auth::{Access, Role, Viewer};
use crate::db::{self, flow as fdb};
use crate::Shared;
use askama::Template;
use axum::extract::{Form, Path, Query, State};
use axum::response::{IntoResponse, Redirect, Response};
use axum::Json;
use serde::Deserialize;

pub struct RunRow {
    pub r: fdb::Run,
    pub duration: String,
    pub jobs: Vec<(String, String)>,
    /// "3rd in line" for a run still waiting for a runner.
    pub place: Option<String>,
}

#[derive(Template)]
#[template(path = "flow_runs.html")]
pub struct RunsPage {
    shell: Shell,
    repo: RepoShell,
    runs: Vec<RunRow>,
    enabled: bool,
    older: Option<i64>,
    /// Writers may start runs: the bookmarks to offer, default first.
    can_run: bool,
    bookmarks: Vec<String>,
    error: Option<String>,
    /// Why this viewer is not offered "Run pipeline", when they are not.
    why_not: Option<String>,
}

#[derive(Deserialize)]
pub struct RunsQuery {
    before: Option<i64>,
    /// Why a "Run pipeline" or "Re-run" did not start.
    error: Option<String>,
}

/// Why `viewer` may not start runs here, or `None` when they may.
pub fn why_not_run(enabled: bool, signed_in: bool, role: Role) -> Option<String> {
    if !enabled {
        Some("Flow is off for this repository; a site administrator can turn it on in Settings → Flow.".into())
    } else if !signed_in {
        Some("Sign in with write access to run the pipeline.".into())
    } else if role < Role::Write {
        Some("Running the pipeline needs write access to this repository.".into())
    } else {
        None
    }
}

const PER_PAGE: i64 = 30;

pub async fn runs(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name)): Path<(String, String)>,
    Query(q): Query<RunsQuery>,
) -> Result<Page<RunsPage>, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow"), &viewer);
    let (_repo, row, role) = lookup(&app, &shell, &viewer, &owner, &name).await?;
    let list = fdb::runs(&app.db, row.id, PER_PAGE + 1, q.before).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let older = (list.len() as i64 > PER_PAGE).then(|| list[PER_PAGE as usize - 1].id);
    let queue = if list.iter().any(|r| r.live()) { fdb::queue(&app.db).await.unwrap_or_default() } else { vec![] };
    let mut runs = Vec::new();
    for r in list.into_iter().take(PER_PAGE as usize) {
        let place = if r.live() { crate::flow::queue_info(&queue, row.id, r.id).place() } else { None };
        let jobs = fdb::jobs(&app.db, r.id).await.unwrap_or_default();
        let duration = match r.finished_ms {
            Some(f) => crate::flow::human_ms(f - r.created_ms),
            None if r.live() => crate::flow::human_ms(db::now_ms() - r.created_ms),
            None => "–".into(),
        };
        runs.push(RunRow { jobs: jobs.into_iter().map(|j| (j.name, j.status)).collect(), duration, r, place });
    }
    let enabled = crate::flow::enabled(&app, &row);
    let why_not = why_not_run(enabled, viewer.account().is_some(), role);
    let can_run = why_not.is_none();
    let bookmarks = if can_run { bookmark_names(&app, &row).await } else { vec![] };
    Ok(Page(RunsPage {
        shell,
        repo: RepoShell::new(&app, &row, "flow").with_role(role),
        runs,
        enabled,
        older,
        can_run,
        bookmarks,
        error: q.error,
        why_not,
    }))
}

/// The repository's bookmarks, its default first.
async fn bookmark_names(app: &Shared, row: &db::repos::RepoRow) -> Vec<String> {
    let Some(repo) = crate::repos::RepoName::new(&row.owner, &row.name) else { return vec![] };
    let mut names: Vec<String> = app.repos.read(&repo, |r, _| Ok(r.view()?.bookmarks.keys().cloned().collect())).await.unwrap_or_default();
    names.sort_by_key(|n| (n != &row.default_bookmark, n.clone()));
    names
}

#[derive(Deserialize)]
pub struct StartForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
    #[serde(default)]
    bookmark: String,
    /// A change's full hash: run the state whose only head it is.
    #[serde(default)]
    change: String,
}

/// `POST /{owner}/{name}/flow/start`: "Run pipeline" on a bookmark's
/// current state, or on one committed change.
pub async fn start(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name)): Path<(String, String)>,
    Form(f): Form<StartForm>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow"), &viewer);
    let me = require(&viewer, &shell)?;
    let (_, row, _) = lookup_role(&app, &shell, &viewer, &owner, &name, Access::Write).await?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let (started, what) = if f.change.trim().is_empty() {
        (crate::flow::run_bookmark(&app, &row, f.bookmark.trim(), &me.account.username, &[]).await, f.bookmark.trim().to_string())
    } else {
        (crate::flow::run_change(&app, &row, &f.change, &me.account.username, &[]).await, format!("change {}", f.change.trim()))
    };
    Ok(match started {
        Ok(n) => {
            db::accounts::audit(&app.db, Some(&me.account), "flow.run", &format!("{owner}/{name}"), &format!("#{n} {what}")).await.ok();
            Redirect::to(&format!("/{owner}/{name}/flow/{n}")).into_response()
        }
        Err(msg) => Redirect::to(&format!("/{owner}/{name}/flow?error={}", urlencoding(&msg))).into_response(),
    })
}

#[derive(Deserialize)]
pub struct RerunForm {
    #[serde(rename = "_csrf")]
    csrf_token: String,
}

/// `POST /{owner}/{name}/flow/{number}/rerun`.
pub async fn rerun(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, number)): Path<(String, String, i64)>,
    Form(f): Form<RerunForm>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow/{number}"), &viewer);
    let me = require(&viewer, &shell)?;
    let (_, row, _) = lookup_role(&app, &shell, &viewer, &owner, &name, Access::Write).await?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let run = fdb::run(&app.db, row.id, number)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?
        .ok_or_else(|| Error::not_found(shell.clone()))?;
    Ok(match crate::flow::rerun(&app, &row, &run, &me.account.username).await {
        Ok(n) => {
            db::accounts::audit(&app.db, Some(&me.account), "flow.rerun", &format!("{owner}/{name}"), &format!("#{n} of #{number}"))
                .await
                .ok();
            Redirect::to(&format!("/{owner}/{name}/flow/{n}")).into_response()
        }
        Err(msg) => Redirect::to(&format!("/{owner}/{name}/flow?error={}", urlencoding(&msg))).into_response(),
    })
}

/// `POST /{owner}/{name}/flow/{number}/jobs/{job}/rerun` (oxygenflow#31).
pub async fn rerun_job(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, number, job)): Path<(String, String, i64, String)>,
    Form(f): Form<RerunForm>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow/{number}"), &viewer);
    let me = require(&viewer, &shell)?;
    let (_, row, _) = lookup_role(&app, &shell, &viewer, &owner, &name, Access::Write).await?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let run = fdb::run(&app.db, row.id, number)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?
        .ok_or_else(|| Error::not_found(shell.clone()))?;
    Ok(match crate::flow::rerun_job(&app, &row, &run, &job, &me.account.username).await {
        Ok(_) => {
            db::accounts::audit(&app.db, Some(&me.account), "flow.rerun", &format!("{owner}/{name}"), &format!("{job} of #{number}"))
                .await
                .ok();
            Redirect::to(&format!("/{owner}/{name}/flow/{number}")).into_response()
        }
        Err(msg) => Redirect::to(&format!("/{owner}/{name}/flow?error={}", urlencoding(&msg))).into_response(),
    })
}

/// `POST /{owner}/{name}/flow/{number}/cancel` (oxygenflow#32).
pub async fn cancel(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, number)): Path<(String, String, i64)>,
    Form(f): Form<RerunForm>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow/{number}"), &viewer);
    let me = require(&viewer, &shell)?;
    let (_, row, _) = lookup_role(&app, &shell, &viewer, &owner, &name, Access::Write).await?;
    csrf(&viewer, &f.csrf_token, &shell)?;
    let run = fdb::run(&app.db, row.id, number)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?
        .ok_or_else(|| Error::not_found(shell.clone()))?;
    Ok(match crate::flow::cancel(&app, &row, &run, &me.account.username).await {
        Ok(()) => {
            db::accounts::audit(&app.db, Some(&me.account), "flow.cancel", &format!("{owner}/{name}"), &format!("#{number}")).await.ok();
            Redirect::to(&format!("/{owner}/{name}/flow/{number}")).into_response()
        }
        Err(msg) => Redirect::to(&format!("/{owner}/{name}/flow?error={}", urlencoding(&msg))).into_response(),
    })
}

/// Percent-encode a message for a query string.
fn urlencoding(s: &str) -> String {
    s.bytes()
        .map(|b| match b {
            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'.' | b'_' | b'~' => (b as char).to_string(),
            _ => format!("%{b:02X}"),
        })
        .collect()
}

/// A job placed in the graph.
pub struct Node {
    pub j: fdb::Job,
    pub x: i64,
    pub y: i64,
    pub duration: String,
}

pub struct Edge {
    pub d: String,
    pub status: String,
}

pub struct Graph {
    pub nodes: Vec<Node>,
    pub edges: Vec<Edge>,
    pub width: i64,
    pub height: i64,
}

pub const NODE_W: i64 = 200;
pub const NODE_H: i64 = 48;
const COL_GAP: i64 = 72;
const ROW_GAP: i64 = 18;
const PAD: i64 = 12;

/// Columns by dependency depth, jobs in each column in name order.
pub fn layout(jobs: Vec<fdb::Job>) -> Graph {
    let mut by_depth: std::collections::BTreeMap<i64, Vec<fdb::Job>> = Default::default();
    for j in jobs {
        by_depth.entry(j.depth).or_default().push(j);
    }
    let rows = by_depth.values().map(Vec::len).max().unwrap_or(0) as i64;
    let height = PAD * 2 + rows * NODE_H + (rows - 1).max(0) * ROW_GAP;
    let mut nodes = Vec::new();
    for (col, (_, mut js)) in by_depth.into_iter().enumerate() {
        js.sort_by(|a, b| a.name.cmp(&b.name));
        let n = js.len() as i64;
        let column_h = n * NODE_H + (n - 1).max(0) * ROW_GAP;
        let top = (height - column_h) / 2;
        for (i, j) in js.into_iter().enumerate() {
            let duration = crate::flow::duration(&j);
            nodes.push(Node { x: PAD + col as i64 * (NODE_W + COL_GAP), y: top + i as i64 * (NODE_H + ROW_GAP), duration, j });
        }
    }
    let mut edges = Vec::new();
    for n in &nodes {
        for d in n.j.depends_on() {
            if let Some(from) = nodes.iter().find(|m| m.j.name == d) {
                let (x1, y1) = (from.x + NODE_W, from.y + NODE_H / 2);
                let (x2, y2) = (n.x, n.y + NODE_H / 2);
                let mid = (x1 + x2) / 2;
                edges.push(Edge { d: format!("M{x1},{y1} C{mid},{y1} {mid},{y2} {x2},{y2}"), status: from.j.status.clone() });
            }
        }
    }
    let cols = nodes.iter().map(|n| n.x).max().map(|x| x + NODE_W + PAD).unwrap_or(PAD * 2);
    Graph { nodes, edges, width: cols, height: height.max(NODE_H + PAD * 2) }
}

pub fn glyph(status: &str) -> &'static str {
    match status {
        "passed" => "✓",
        "failed" => "✕",
        "running" => "●",
        "skipped" => "⤼",
        "cancelled" => "⊘",
        "error" => "!",
        _ => "○",
    }
}

/// Failed tests a run page lists per job; the rest are counted.
const SHOWN_FAILURES: i64 = 50;

/// A stretch of a job's log as the run page shows it: a line, or a
/// section the job marked with `::group::TITLE` … `::endgroup::`
/// (oxygenflow#31), shown folded with how long it took.
pub enum Segment {
    Line(fdb::LogLine),
    Group(Section),
}

pub struct Section {
    pub title: String,
    /// When it began, and ended (`None` while it is still going).
    pub from_t: i64,
    pub to_t: Option<i64>,
    pub lines: Vec<fdb::LogLine>,
}

/// A log's lines in sections. A section left open is still going; a new
/// `::group::` ends the one before (sections do not nest).
pub fn sections(lines: &[fdb::LogLine]) -> Vec<Segment> {
    let mut out: Vec<Segment> = Vec::new();
    let mut open: Option<Section> = None;
    for l in lines {
        if let Some(title) = l.text.strip_prefix("::group::") {
            if let Some(g) = open.take() {
                out.push(Segment::Group(Section { to_t: Some(l.t), ..g }));
            }
            open = Some(Section { title: title.trim().to_string(), from_t: l.t, to_t: None, lines: Vec::new() });
        } else if l.text.trim() == "::endgroup::" {
            if let Some(g) = open.take() {
                out.push(Segment::Group(Section { to_t: Some(l.t), ..g }));
            }
        } else {
            match open.as_mut() {
                Some(g) => g.lines.push(l.clone()),
                None => out.push(Segment::Line(l.clone())),
            }
        }
    }
    if let Some(g) = open {
        out.push(Segment::Group(g));
    }
    out
}

/// Milliseconds as the log shows them: `12.3s`.
pub fn secs(ms: impl std::borrow::Borrow<i64>) -> String {
    let ms = *ms.borrow();
    format!("{}.{}s", ms / 1000, ms % 1000 / 100)
}

pub struct JobLog {
    pub j: fdb::Job,
    pub artifacts: Vec<fdb::Artifact>,
    pub lines: Vec<fdb::LogLine>,
    /// The lines in sections (oxygenflow#31).
    pub segments: Vec<Segment>,
    pub duration: String,
    /// The last line shown; the live view asks for what follows.
    pub last_seq: i64,
    /// The job's coverage report, when it uploaded one (#113): its id and percentage.
    pub coverage: Option<(i64, String)>,
    /// The job's test report, when it uploaded one (#114), and its first
    /// failures.
    pub tests: Option<crate::junit::Report>,
    pub failures: Vec<crate::junit::Case>,
}

#[derive(Template)]
#[template(path = "flow_run.html")]
pub struct RunPage {
    shell: Shell,
    repo: RepoShell,
    run: fdb::Run,
    graph: Graph,
    logs: Vec<JobLog>,
    duration: String,
    /// Whether the viewer may re-run it.
    can_rerun: bool,
    /// Whether the viewer may cancel it.
    can_cancel: bool,
    /// Where a live run stands among the runners' work.
    queue: Option<crate::flow::QueueInfo>,
    /// Releases a writer may attach this run's artifacts to.
    releases: Vec<db::releases::Release>,
}

/// Lines of a job's log a page shows before "the rest is loaded as it comes".
const PAGE_LINES: i64 = 5000;

pub async fn run(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, id)): Path<(String, String, i64)>,
) -> Result<Page<RunPage>, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow/{id}"), &viewer);
    let (_repo, row, role) = lookup(&app, &shell, &viewer, &owner, &name).await?;
    let run = fdb::run(&app.db, row.id, id)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?
        .ok_or_else(|| Error::not_found(shell.clone()))?;
    let jobs = fdb::jobs(&app.db, run.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let reports = crate::coverage::for_run(&app.db, run.id).await.unwrap_or_default();
    let test_reports = crate::junit::for_run(&app.db, run.id).await.unwrap_or_default();
    let mut logs = Vec::new();
    for j in &jobs {
        let lines = fdb::log(&app.db, j.id, 0, PAGE_LINES).await.unwrap_or_default();
        let last_seq = lines.last().map(|l| l.seq).unwrap_or(0);
        let artifacts = fdb::artifacts(&app.db, j.id).await.unwrap_or_default();
        let coverage = reports
            .iter()
            .find(|r| r.job_id == Some(j.id))
            .map(|r| (r.id, r.percent().map(|p| format!("{p:.1}%")).unwrap_or_else(|| "no lines".into())));
        let tests = test_reports.iter().find(|r| r.job_id == j.id).cloned();
        let failures = match &tests {
            Some(r) if r.broken() > 0 => crate::junit::failures(&app.db, r.id, SHOWN_FAILURES).await.unwrap_or_default(),
            _ => vec![],
        };
        let segments = sections(&lines);
        logs.push(JobLog {
            duration: crate::flow::duration(j),
            j: j.clone(),
            artifacts,
            lines,
            segments,
            last_seq,
            coverage,
            tests,
            failures,
        });
    }
    let duration = match run.finished_ms {
        Some(f) => crate::flow::human_ms(f - run.created_ms),
        None => crate::flow::human_ms(db::now_ms() - run.created_ms),
    };
    let graph = layout(jobs);
    let can_write = viewer.account().is_some() && role >= Role::Write;
    let can_rerun = !run.live() && can_write && crate::flow::enabled(&app, &row);
    let can_cancel = run.live() && can_write;
    let queue = if run.live() {
        let q = fdb::queue(&app.db).await.unwrap_or_default();
        Some(crate::flow::queue_info(&q, row.id, run.id)).filter(|i| i.position.is_some())
    } else {
        None
    };
    let releases = if viewer.account().is_some() && role >= Role::Write && logs.iter().any(|l| !l.artifacts.is_empty()) {
        db::releases::list(&app.db, row.id).await.unwrap_or_default()
    } else {
        vec![]
    };
    Ok(Page(RunPage {
        shell,
        repo: RepoShell::new(&app, &row, "flow").with_role(role),
        run,
        graph,
        logs,
        duration,
        can_rerun,
        can_cancel,
        queue,
        releases,
    }))
}

#[derive(Deserialize)]
pub struct LiveQuery {
    /// `job:seq,job:seq`: the last log line each open job already shows.
    after: Option<String>,
}

/// `GET /{owner}/{name}/flow/{id}/live`: statuses and new log lines, for the
/// run page while it is live.
pub async fn live(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, id)): Path<(String, String, i64)>,
    Query(q): Query<LiveQuery>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, "", &viewer);
    let (_repo, row, _role) = lookup(&app, &shell, &viewer, &owner, &name).await?;
    let run = fdb::run(&app.db, row.id, id)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?
        .ok_or_else(|| Error::not_found(shell.clone()))?;
    let jobs = fdb::jobs(&app.db, run.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let after: std::collections::HashMap<i64, i64> = q
        .after
        .unwrap_or_default()
        .split(',')
        .filter_map(|p| p.split_once(':'))
        .filter_map(|(a, b)| Some((a.parse().ok()?, b.parse().ok()?)))
        .collect();
    let mut out = Vec::new();
    for j in &jobs {
        let lines = match after.get(&j.id) {
            Some(seq) => fdb::log(&app.db, j.id, *seq, 1000).await.unwrap_or_default(),
            None => vec![],
        };
        out.push(serde_json::json!({
            "id": j.id,
            "name": j.name,
            "status": j.status,
            "glyph": glyph(&j.status),
            "duration": crate::flow::duration(j),
            "exit_code": j.exit_code,
            "lines": lines.iter().map(|l| serde_json::json!({ "seq": l.seq, "t": l.t, "stream": l.stream, "text": l.text })).collect::<Vec<_>>(),
        }));
    }
    Ok(Json(serde_json::json!({ "status": run.status, "live": run.live(), "jobs": out })).into_response())
}

// ------------------------------------------------------------ state stamps

/// In rendered Markdown, the image path that is the viewed state's stamp.
pub const STAMP_IMAGE: &str = ".flow/stamp";
/// In rendered Markdown, the link path to the viewed state's run.
pub const RUN_LINK: &str = ".flow/run";

/// Resolve a ref to its state address, and whether the ref can move.
async fn state_of(app: &Shared, owner: &str, name: &str, r: &str) -> Result<(String, bool), crate::repos::RepoError> {
    let repo = crate::repos::RepoName::new(owner, name).ok_or(crate::repos::RepoError::NotFound)?;
    let spec = r.to_string();
    app.repos
        .read(&repo, move |repo, cache| {
            let t = crate::repos::view::resolve(repo, cache, &spec)?;
            let moves = matches!(t.kind, crate::repos::view::RefKind::Bookmark | crate::repos::view::RefKind::Tag);
            Ok((t.permalink().unwrap_or_default(), moves))
        })
        .await
}

/// `GET /{owner}/{name}/flow/stamp/{ref}` (hub spec §13.2).
pub async fn stamp(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, r)): Path<(String, String, String)>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, "", &viewer);
    let (_repo, row, _role) = lookup(&app, &shell, &viewer, &owner, &name).await?;
    let (heads, moves) = state_of(&app, &owner, &name, &r).await.map_err(|e| Error::from_repo(shell.clone(), e))?;
    if moves && !heads.is_empty() {
        let mut res = axum::response::Redirect::to(&format!("/{owner}/{name}/flow/stamp/{heads}")).into_response();
        res.headers_mut().insert(axum::http::header::CACHE_CONTROL, axum::http::HeaderValue::from_static("no-cache"));
        return Ok(res);
    }
    let run = fdb::latest_for_heads(&app.db, row.id, &heads).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let jobs = match &run {
        Some(r) => fdb::jobs(&app.db, r.id).await.map_err(|e| Error::from_db(shell.clone(), e))?,
        None => vec![],
    };
    let svg = stamp_svg(&heads, run.as_ref(), &jobs);
    let cache = if run.as_ref().is_some_and(|r| !r.live()) { "public, max-age=3600" } else { "public, max-age=60" };
    Ok((
        [
            (axum::http::header::CONTENT_TYPE, "image/svg+xml; charset=utf-8"),
            (axum::http::header::CACHE_CONTROL, cache),
            (axum::http::header::CONTENT_SECURITY_POLICY, "default-src 'none'; style-src 'unsafe-inline'"),
        ],
        svg,
    )
        .into_response())
}

/// `GET /{owner}/{name}/flow/at/{ref}`: the run of the ref's state, or the Flow tab.
pub async fn at(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, r)): Path<(String, String, String)>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, "", &viewer);
    let (_repo, row, _role) = lookup(&app, &shell, &viewer, &owner, &name).await?;
    let (heads, _) = state_of(&app, &owner, &name, &r).await.map_err(|e| Error::from_repo(shell.clone(), e))?;
    let run = fdb::latest_for_heads(&app.db, row.id, &heads).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let to = match run {
        Some(r) => format!("/{owner}/{name}/flow/{}", r.number),
        None => format!("/{owner}/{name}/flow"),
    };
    Ok(axum::response::Redirect::to(&to).into_response())
}

fn xml(s: &str) -> String {
    s.replace('&', "&amp;").replace('<', "&lt;").replace('>', "&gt;").replace('"', "&quot;")
}

/// The stamp: the mark, one glyph per job, the status, the state and the
/// date; the same facts machine-readable in `<metadata>`. Fixed colours,
/// because an image does not follow the page's theme.
pub fn stamp_svg(heads: &str, run: Option<&fdb::Run>, jobs: &[fdb::Job]) -> String {
    const CH: f64 = 6.6; // IBM Plex Mono at 11px
    let colour = |s: &str| match s {
        "passed" => "#5fe3a1",
        "failed" | "error" => "#ff5e7a",
        "running" => "#00e0f0",
        _ => "#8592ad",
    };
    let short: String = heads.chars().take(12).collect();
    let (status, date) = match run {
        Some(r) => (r.status.as_str(), crate::render::time::absolute(r.created_ms as u64).chars().take(10).collect::<String>()),
        None => ("no run", String::new()),
    };
    let mut ordered: Vec<&fdb::Job> = jobs.iter().collect();
    ordered.sort_by(|a, b| (a.depth, &a.name).cmp(&(b.depth, &b.name)));
    let label = "OXYGENFLOW";
    let label_w = 18.0 + label.len() as f64 * 7.4 + 8.0; // Barlow bold 10.5px, spaced
    let glyphs_w = if ordered.is_empty() { 0.0 } else { ordered.len() as f64 * 10.0 + 6.0 };
    let tail = if date.is_empty() { format!("{status} · {short}") } else { format!("{status} · {short} · {date}") };
    let right_w = 8.0 + glyphs_w + tail.chars().count() as f64 * CH + 8.0;
    let w = (label_w + right_w).ceil();
    let mut glyphs = String::new();
    for (i, j) in ordered.iter().enumerate() {
        let x = label_w + 8.0 + i as f64 * 10.0 + 4.0;
        glyphs.push_str(&format!(
            r#"<text x="{x:.1}" y="15" fill="{}" text-anchor="middle">{}</text>"#,
            colour(&j.status),
            glyph(&j.status)
        ));
    }
    let meta = serde_json::json!({
        "heads": heads.split('+').filter(|h| !h.is_empty()).collect::<Vec<_>>(),
        "run": run.map(|r| r.number),
        "status": status,
        "jobs": ordered.iter().map(|j| serde_json::json!({ "name": j.name, "status": j.status, "receipt": j.receipt_hash })).collect::<Vec<_>>(),
    });
    let title = match run {
        Some(r) => format!("OxygenFlow run #{} {status} on state {short}", r.number),
        None => format!("OxygenFlow: no run for state {short}"),
    };
    format!(
        r##"<svg xmlns="http://www.w3.org/2000/svg" width="{w}" height="22" viewBox="0 0 {w} 22" role="img" aria-label="{t}"><title>{t}</title><metadata>{m}</metadata><rect width="{w}" height="22" rx="4" fill="#0e1526"/><rect width="{lw:.1}" height="22" rx="4" fill="#0b3f9e"/><rect x="{lx:.1}" width="4" height="22" fill="#0b3f9e"/><circle cx="9" cy="11" r="3.2" fill="none" stroke="#00f0ff" stroke-width="1.6"/><text x="16" y="15" fill="#ffffff" font-family="Barlow, Verdana, sans-serif" font-size="10.5" font-weight="700" letter-spacing=".6">{label}</text><g font-family="IBM Plex Mono, ui-monospace, monospace" font-size="11">{glyphs}<text x="{tx:.1}" y="15" fill="{sc}">{tail}</text></g><rect x=".5" y=".5" width="{wi}" height="21" rx="3.5" fill="none" stroke="#1f2b47"/></svg>"##,
        t = xml(&title),
        m = xml(&meta.to_string()),
        lw = label_w,
        lx = label_w - 4.0,
        tx = label_w + 8.0 + glyphs_w,
        sc = colour(status),
        tail = xml(&tail),
        wi = w - 1.0,
    )
}

/// A receipt kept in a repository (Oxygen spec §14.6), as pages show it.
#[derive(Clone, Debug)]
pub struct ReceiptRow {
    pub attest: String,
    pub job: String,
    pub exit_code: u32,
    pub duration: String,
    pub runner: String,
    pub run: String,
    /// Why it does not verify, or that its runner's key was revoked.
    pub problem: String,
    pub made_ms: i64,
}

impl ReceiptRow {
    pub fn passed(&self) -> bool {
        self.exit_code == 0
    }
}

/// The receipts kept for the state of `heads`.
pub async fn receipts_of(app: &Shared, name: &crate::repos::RepoName, heads: Vec<oxy_core::hash::ChangeHash>) -> Vec<ReceiptRow> {
    let base = app.config.base_url();
    let found = app.repos.read(name, move |repo, _| Ok(repo.receipts(&heads)?)).await.unwrap_or_default();
    found
        .into_iter()
        .map(|i| {
            let r = &i.signed.receipt;
            let run = i.signed.run().to_string();
            ReceiptRow {
                attest: i.attest.to_hex(),
                job: r.job_name.clone(),
                exit_code: r.exit_code,
                duration: crate::flow::human_ms(r.duration_ms as i64),
                runner: i.signed.runner.name.clone(),
                // Only links to this hub are followed from the page.
                run: if run.starts_with(base) { run } else { String::new() },
                problem: match (i.problem, i.revoked) {
                    (Some(p), _) => p,
                    (None, true) => "the runner's key was revoked".into(),
                    (None, false) => String::new(),
                },
                made_ms: i.signed.attest.hlc.wall_ms as i64,
            }
        })
        .collect()
}

/// `GET /{owner}/{name}/receipts/{attest}`: a signed receipt, for
/// `oxy receipt verify` or `oxy receipt import`.
pub async fn receipt_file(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, attest)): Path<(String, String, String)>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/receipts/{attest}"), &viewer);
    let (repo, _row, _role) = lookup(&app, &shell, &viewer, &owner, &name).await?;
    let Some(r) = oxy_core::hash::ObjectRef::from_hex(attest.trim_end_matches(".receipt")) else {
        return Err(Error::not_found(shell));
    };
    let (job, bytes) = app
        .repos
        .read(&repo, move |repo, _| {
            let i = repo.receipt(&r)?;
            Ok((i.signed.receipt.job_name.clone(), i.signed.encode()))
        })
        .await
        .map_err(|_| Error::not_found(shell.clone()))?;
    let file: String = job.chars().filter(|c| c.is_ascii_alphanumeric() || matches!(c, '-' | '_' | '.')).collect();
    Ok((
        [
            (axum::http::header::CONTENT_TYPE, "application/oxy-receipt".to_string()),
            (axum::http::header::CONTENT_DISPOSITION, format!("attachment; filename=\"{file}-{}.receipt\"", r.short(12))),
        ],
        bytes,
    )
        .into_response())
}

/// `GET /{owner}/{name}/flow/{id}/artifacts/{job}/{artifact}`: an artifact
/// of a run's job, read from the repository.
pub async fn artifact_file(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, id, job, artifact)): Path<(String, String, i64, String, String)>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow/{id}/artifacts/{job}/{artifact}"), &viewer);
    let (repo, row, _role) = lookup(&app, &shell, &viewer, &owner, &name).await?;
    let run = fdb::run(&app.db, row.id, id)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?
        .ok_or_else(|| Error::not_found(shell.clone()))?;
    let jobs = fdb::jobs(&app.db, run.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let Some(j) = jobs.iter().find(|j| j.name == job) else { return Err(Error::not_found(shell)) };
    let arts = fdb::artifacts(&app.db, j.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let Some(a) = arts.into_iter().find(|a| a.name == artifact) else { return Err(Error::not_found(shell)) };
    let Some(blob) = oxy_core::hash::ObjectRef::from_hex(&a.blob) else { return Err(Error::not_found(shell)) };
    let bytes = app.repos.read(&repo, move |r, _| Ok(r.read_blob(&blob)?)).await.map_err(|_| Error::not_found(shell.clone()))?;
    let file = a.path.rsplit('/').next().unwrap_or(&a.name).to_string();
    Ok((
        [
            (axum::http::header::CONTENT_TYPE, "application/octet-stream".to_string()),
            (axum::http::header::CONTENT_DISPOSITION, format!("attachment; filename=\"{}\"", file.replace('"', ""))),
        ],
        bytes,
    )
        .into_response())
}

#[derive(Deserialize)]
pub struct AttachForm {
    _csrf: String,
    release: i64,
}

/// `POST /{owner}/{name}/flow/{id}/artifacts/{job}/{artifact}/attach`: add
/// an artifact to a release as an asset, named after its path; the release
/// page then shows the run and receipt that built it.
pub async fn attach(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name, id, job, artifact)): Path<(String, String, i64, String, String)>,
    Form(f): Form<AttachForm>,
) -> Result<Response, Error> {
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow/{id}"), &viewer);
    require(&viewer, &shell)?;
    csrf(&viewer, &f._csrf, &shell)?;
    let (repo, row, _) = lookup_role(&app, &shell, &viewer, &owner, &name, Access::Write).await?;
    let run = fdb::run(&app.db, row.id, id)
        .await
        .map_err(|e| Error::from_db(shell.clone(), e))?
        .ok_or_else(|| Error::not_found(shell.clone()))?;
    let jobs = fdb::jobs(&app.db, run.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let Some(j) = jobs.iter().find(|j| j.name == job) else { return Err(Error::not_found(shell)) };
    // A failing job's `when "always"` artifacts are not in its receipt, so
    // they cannot stand for a release (oxygenflow#37).
    if j.status != "passed" {
        return Err(Error::bad(shell, "only a passing job's artifacts can be attached to a release"));
    }
    let arts = fdb::artifacts(&app.db, j.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let Some(a) = arts.into_iter().find(|a| a.name == artifact) else { return Err(Error::not_found(shell)) };
    let releases = db::releases::list(&app.db, row.id).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let Some(rel) = releases.into_iter().find(|r| r.id == f.release) else { return Err(Error::not_found(shell)) };
    let Some(blob) = oxy_core::hash::ObjectRef::from_hex(&a.blob) else { return Err(Error::not_found(shell)) };
    let bytes = app.repos.read(&repo, move |r, _| Ok(r.read_blob(&blob)?)).await.map_err(|e| Error::from_repo(shell.clone(), e))?;
    let file = a.path.rsplit('/').next().unwrap_or(&a.name).to_string();
    super::releases::store_asset(&app, rel.id, &file, "application/octet-stream", &bytes)
        .await
        .map_err(|m| Error::bad(shell.clone(), m))?;
    Ok(Redirect::to(&format!("/{owner}/{name}/releases/tag/{}", rel.tag)).into_response())
}

/// `/{owner}/{name}/flow/badge.svg`: the latest run on the default
/// bookmark as a small SVG for a README, for whoever may read the
/// repository. `passed` green, `failed` or `error` red, a run still going
/// blue, none grey.
pub async fn badge(
    State(app): State<Shared>,
    viewer: Viewer,
    Path((owner, name)): Path<(String, String)>,
) -> Result<axum::response::Response, Error> {
    use axum::response::IntoResponse;
    let shell = Shell::new(&app, &format!("/{owner}/{name}/flow"), &viewer);
    let (_repo, row, _role) = lookup(&app, &shell, &viewer, &owner, &name).await?;
    let latest = fdb::latest_on(&app.db, row.id, &row.default_bookmark).await.map_err(|e| Error::from_db(shell.clone(), e))?;
    let (text, colour) = match latest.as_ref().map(|r| r.status.as_str()) {
        Some("passed") => ("passing", "#2da44e"),
        Some("failed") | Some("error") => ("failing", "#cf222e"),
        Some("cancelled") => ("cancelled", "#6e7781"),
        Some(_) => ("running", "#0969da"),
        None => ("no runs", "#6e7781"),
    };
    let label = "OxygenFlow";
    let (lw, tw) = (label.len() as u32 * 7 + 10, text.len() as u32 * 7 + 10);
    let svg = format!(
        r##"<svg xmlns="http://www.w3.org/2000/svg" width="{w}" height="20" role="img" aria-label="{label}: {text}"><title>{label}: {text}</title><rect width="{lw}" height="20" rx="3" fill="#555"/><rect x="{lw}" width="{tw}" height="20" rx="3" fill="{colour}"/><rect x="{lw}" width="4" height="20" fill="{colour}"/><g fill="#fff" font-family="Verdana,DejaVu Sans,sans-serif" font-size="11" text-anchor="middle"><text x="{lx}" y="14">{label}</text><text x="{tx}" y="14">{text}</text></g></svg>"##,
        w = lw + tw,
        lx = lw / 2,
        tx = lw + tw / 2,
    );
    Ok((
        [(axum::http::header::CONTENT_TYPE, "image/svg+xml; charset=utf-8"), (axum::http::header::CACHE_CONTROL, "no-cache, max-age=60")],
        svg,
    )
        .into_response())
}

#[cfg(test)]
mod section_tests {
    use super::*;

    fn line(seq: i64, t: i64, text: &str) -> fdb::LogLine {
        fdb::LogLine { seq, t, stream: "out".into(), text: text.into() }
    }

    #[test]
    fn marked_lines_fold_into_sections() {
        let lines = vec![
            line(1, 0, "booting"),
            line(2, 100, "::group::cargo build"),
            line(3, 200, "Compiling a"),
            line(4, 900, "Compiling b"),
            line(5, 4_300, "::endgroup::"),
            line(6, 4_400, "::group::cargo test"),
            line(7, 4_500, "test x ... ok"),
            line(8, 5_000, "::group::lint"),
            line(9, 5_100, "clean"),
        ];
        let segs = sections(&lines);
        assert_eq!(segs.len(), 4);
        assert!(matches!(&segs[0], Segment::Line(l) if l.text == "booting"));
        let Segment::Group(build) = &segs[1] else { panic!("a section") };
        assert_eq!((build.title.as_str(), build.from_t, build.to_t, build.lines.len()), ("cargo build", 100, Some(4_300), 2));
        let Segment::Group(test) = &segs[2] else { panic!("a section") };
        assert_eq!(test.to_t, Some(5_000), "a new section ends the one before");
        let Segment::Group(lint) = &segs[3] else { panic!("a section") };
        assert_eq!((lint.to_t, lint.lines.len()), (None, 1), "still going");
        assert_eq!(secs(4_200), "4.2s");
    }
}