//! History, change and compare pages.

use super::{filters, lookup, Error, Page, RepoShell, Shell};

use crate::auth::Viewer;

use crate::render::{self, diff, graph};

use crate::repos::view;

use crate::Shared;

use askama::Template;

use axum::extract::{Path, Query, State};

use axum::response::{IntoResponse, Response};

use oxy_core::repo::FileDiff;

use serde::Deserialize;

use std::collections::BTreeMap;

const PAGE: usize = 50;

#[derive(Deserialize)]

pub struct HistoryQuery {

    path: Option<String>,

    offset: Option<usize>,

}

#[derive(Template)]

#[template(path = "history.html")]

pub struct HistoryPage {

    shell: Shell,

    repo: RepoShell,

    h: view::History,

    rows: Vec<graph::Row>,

    lanes: usize,

}

pub async fn history(

    State(app): State<Shared>,

    viewer: Viewer,

    Path((owner, name, r)): Path<(String, String, String)>,

    Query(q): Query<HistoryQuery>,

) -> Result<Page<HistoryPage>, Error> {

    let shell = Shell::new(&app, &format!("/{owner}/{name}/changes/{r}"), &viewer);

    let (repo, row, role) = lookup(&app, &shell, &viewer, &owner, &name).await?;

    let spec = r.clone();

    let path = q.path.clone().filter(|p| !p.is_empty());

    let offset = q.offset.unwrap_or(0);

    let h = app

        .repos

        .read(&repo, move |repo, cache| {

            let target = view::resolve(repo, cache, &spec)?;

            view::history(repo, cache, target, path.as_deref(), offset, PAGE)

        })

        .await

        .map_err(|e| Error::from_repo(shell.clone(), e))?;

    let mut h = h;

    super::attribute(&app, &mut h.entries.iter_mut().collect::<Vec<_>>()).await;

    let graph_input: Vec<(String, Vec<String>)> = h.entries.iter().map(|c| (c.hash.clone(), c.deps.clone())).collect();

    let rows = graph::layout(&graph_input);

    let lanes = graph::width(&rows);

    Ok(Page(HistoryPage { shell, repo: RepoShell::new(&app, &row, "changes").with_role(role), h, rows, lanes }))

}

#[derive(Deserialize)]

pub struct FunctionQuery {

    start: usize,

    end: usize,

    #[serde(default)]

    name: String,

}

#[derive(Template)]

#[template(path = "function.html")]

pub struct FunctionPage {

    shell: Shell,

    repo: RepoShell,

    r: String,

    path: String,

    name: String,

    start: usize,

    end: usize,

    entries: Vec<view::ChangeView>,

    rows: Vec<graph::Row>,

    lanes: usize,

}

/// `GET /{owner}/{name}/function/{ref}/{path}?start=…&end=…&name=…`: the

/// history of a function (hub spec §6.6): every change that wrote or

/// deleted one of its lines, exactly (Oxygen spec §27), with a graph of how

/// those changes depend on each other.

pub async fn function(

    State(app): State<Shared>,

    viewer: Viewer,

    Path((owner, name, r, path)): Path<(String, String, String, String)>,

    Query(q): Query<FunctionQuery>,

) -> Result<Page<FunctionPage>, Error> {

    let shell = Shell::new(&app, &format!("/{owner}/{name}/function/{r}/{path}"), &viewer);

    let (repo, row, role) = lookup(&app, &shell, &viewer, &owner, &name).await?;

    let (spec, p, start, end) = (r.clone(), path.clone(), q.start, q.end);

    let mut entries = app

        .repos

        .read(&repo, move |repo, cache| {

            let target = view::resolve(repo, cache, &spec)?;

            let history = repo.line_history(&target.heads, &p, start, end)?;

            let labels = view::head_labels(repo)?;

            Ok(history.iter().map(|e| view::change_view_pub(repo, &e.hash, &e.change, e.is_head, &labels)).collect::<Vec<_>>())

        })

        .await

        .map_err(|e| Error::from_repo(shell.clone(), e))?;

    // The graph shows how these changes depend on one another.

    let listed: std::collections::HashSet<String> = entries.iter().map(|c| c.hash.clone()).collect();

    for c in &mut entries {

        c.deps.retain(|d| listed.contains(d));

    }

    super::attribute(&app, &mut entries.iter_mut().collect::<Vec<_>>()).await;

    let graph_input: Vec<(String, Vec<String>)> = entries.iter().map(|c| (c.hash.clone(), c.deps.clone())).collect();

    let rows = graph::layout(&graph_input);

    let lanes = graph::width(&rows);

    Ok(Page(FunctionPage {

        shell,

        repo: RepoShell::new(&app, &row, "code").with_role(role),

        r,

        path,

        name: q.name,

        start,

        end,

        entries,

        rows,

        lanes,

    }))

}

/// A file's diff, rendered.

pub struct FileRows {

    pub path: String,

    pub from: Option<String>,

    pub kind: String,

    pub lines: Vec<diff::Line>,

    pub added: usize,

    pub removed: usize,

    pub anchor: String,

}

pub fn render_files(files: &[FileDiff], bases: &BTreeMap<String, Vec<u8>>) -> Vec<FileRows> {

    render_files_with(files, bases, diff::Options::default())

}

/// `render_files` with diff options (hub spec §6.4: `?w=1` hides whitespace changes).

pub fn render_files_with(files: &[FileDiff], bases: &BTreeMap<String, Vec<u8>>, opts: diff::Options) -> Vec<FileRows> {

    files

        .iter()

        .enumerate()

        .map(|(i, f)| {

            let base = bases.get(&f.path).map(Vec::as_slice).unwrap_or(b"");

            let lines = diff::unified_with(base, &f.hunks, 3, opts);

            FileRows {

                path: f.path.clone(),

                from: f.from.clone(),

                kind: f.kind.clone(),

                added: lines.iter().filter(|l| l.kind == diff::Kind::Add).count(),

                removed: lines.iter().filter(|l| l.kind == diff::Kind::Del).count(),

                lines,

                anchor: format!("diff-{i}"),

            }

        })

        .collect()

}

#[derive(Template)]

#[template(path = "change.html")]

pub struct ChangePage {

    shell: Shell,

    repo: RepoShell,

    c: view::ChangeDetail,

    files: Vec<FileRows>,

    body_html: String,

    ignore_ws: bool,

}

/// `?w=1` on a diff page hides whitespace-only changes.

#[derive(Deserialize, Default)]

pub struct DiffQuery {

    #[serde(default)]

    w: Option<String>,

}

impl DiffQuery {

    pub fn options(&self) -> diff::Options {

        diff::Options { ignore_whitespace: self.w.as_deref() == Some("1") }

    }

}

pub async fn change(

    State(app): State<Shared>,

    viewer: Viewer,

    Path((owner, name, hash)): Path<(String, String, String)>,

    Query(q): Query<DiffQuery>,

) -> Result<Page<ChangePage>, Error> {

    let shell = Shell::new(&app, &format!("/{owner}/{name}/change/{hash}"), &viewer);

    let (repo, row, role) = lookup(&app, &shell, &viewer, &owner, &name).await?;

    let spec = hash.clone();

    let c = app

        .repos

        .read(&repo, move |repo, cache| {

            let h = view::resolve_change(repo, cache, &spec)?;

            view::change(repo, cache, &h)

        })

        .await

        .map_err(|e| Error::from_repo(shell.clone(), e))?;

    let mut c = c;

    {

        let mut all: Vec<&mut view::ChangeView> = vec![&mut c.view];

        all.extend(c.deps.iter_mut());

        all.extend(c.dependents.iter_mut());

        super::attribute(&app, &mut all).await;

    }

    let files = render_files_with(&c.files, &c.bases, q.options());

    let ignore_ws = q.options().ignore_whitespace;

    let body_html =

        if c.view.body.is_empty() { String::new() } else { format!("<pre class=\"msg\">{}</pre>", render::escape(&c.view.body)) };

    Ok(Page(ChangePage { shell, repo: RepoShell::new(&app, &row, "changes").with_role(role), c, files, body_html, ignore_ws }))

}

#[derive(Template)]

#[template(path = "compare.html")]

pub struct ComparePage {

    shell: Shell,

    repo: RepoShell,

    cmp: view::Compare,

    files: Vec<FileRows>,

    ignore_ws: bool,

    /// The two sides as given, for the pickers.

    base_spec: String,

    head_spec: String,

    /// Bookmarks and tags to pick from.

    bookmarks: Vec<String>,

    tags: Vec<String>,

    propose: Option<Propose>,

}

/// "Propose this": head into base, when both are bookmarks and the viewer may write.

pub struct Propose {

    pub url: String,

    /// An open proposal of head into base already.

    pub existing: Option<i64>,

}

#[derive(Deserialize)]

pub struct CompareForm {

    base: Option<String>,

    head: Option<String>,

}

/// `/compare`: the pickers' form target, or a sensible first comparison:

/// the most recently changed other bookmark against the default.

pub async fn compare_index(

    State(app): State<Shared>,

    viewer: Viewer,

    Path((owner, name)): Path<(String, String)>,

    Query(q): Query<CompareForm>,

) -> Result<Response, Error> {

    let shell = Shell::new(&app, &format!("/{owner}/{name}/compare"), &viewer);

    let (repo, row, _role) = lookup(&app, &shell, &viewer, &owner, &name).await?;

    let clean = |s: Option<String>| s.map(|x| x.trim().to_string()).filter(|x| !x.is_empty() && !x.contains("..."));

    let (base, head) = match (clean(q.base), clean(q.head)) {

        (Some(b), Some(h)) => (b, h),

        (b, h) => {

            let default = row.default_bookmark.clone();

            let d = default.clone();

            let newest = app

                .repos

                .read(&repo, move |r, cache| {

                    Ok(view::bookmarks(r, cache, &d)?.into_iter().filter(|b| !b.default).max_by_key(|b| b.latest_ms).map(|b| b.name))

                })

                .await

                .ok()

                .flatten();

            (b.unwrap_or_else(|| default.clone()), h.unwrap_or_else(|| newest.unwrap_or(default)))

        }

    };

    let enc = |s: &str| s.replace('%', "%25").replace(' ', "%20").replace('?', "%3F").replace('#', "%23");

    Ok(axum::response::Redirect::to(&format!("/{owner}/{name}/compare/{}...{}", enc(&base), enc(&head))).into_response())

}

/// `/compare/{base}...{head}`.

pub async fn compare(

    State(app): State<Shared>,

    viewer: Viewer,

    Path((owner, name, spec)): Path<(String, String, String)>,

    Query(q): Query<DiffQuery>,

) -> Result<Page<ComparePage>, Error> {

    let shell = Shell::new(&app, &format!("/{owner}/{name}/compare/{spec}"), &viewer);

    let (repo, row, role) = lookup(&app, &shell, &viewer, &owner, &name).await?;

    let Some((a, b)) = spec.split_once("...") else {

        return Err(Error::bad(shell, "compare takes base...head"));

    };

    let (a, b) = (a.to_string(), b.to_string());

    let cmp = app

        .repos

        .read(&repo, move |repo, cache| {

            let base = view::resolve(repo, cache, &a)?;

            let head = view::resolve(repo, cache, &b)?;

            view::compare(repo, cache, base, head)

        })

        .await

        .map_err(|e| Error::from_repo(shell.clone(), e))?;

    let mut cmp = cmp;

    super::attribute(&app, &mut cmp.added.iter_mut().collect::<Vec<_>>()).await;

    let files = render_files_with(&cmp.files, &cmp.bases, q.options());

    let ignore_ws = q.options().ignore_whitespace;

    let rs = RepoShell::new(&app, &row, "changes").with_role(role);

    let (bookmarks, tags) = app

        .repos

        .read(&repo, |r, _| {

            let b: Vec<String> = r.bookmarks()?.into_iter().map(|b| b.name).collect();

            let t: Vec<String> = view::tags(r)?.into_iter().map(|t| t.name).collect();

            Ok((b, t))

        })

        .await

        .unwrap_or_default();

    let both_bookmarks = cmp.base.kind == view::RefKind::Bookmark && cmp.head.kind == view::RefKind::Bookmark;

    let propose = if both_bookmarks && cmp.base.label != cmp.head.label && !cmp.added.is_empty() && rs.can(crate::auth::Access::Write) {

        let open = crate::db::proposals::list(&app.db, row.id, &["open"]).await.unwrap_or_default();

        let existing = open

            .iter()

            .find(|p| p.source_kind == "bookmark" && p.source_bookmark == cmp.head.label && p.target == cmp.base.label)

            .map(|p| p.number);

        Some(Propose { url: format!("{}/proposals/new?source={}&target={}", rs.url, cmp.head.label, cmp.base.label), existing })

    } else {

        None

    };

    let (base_spec, head_spec) = spec.split_once("...").map(|(a, b)| (a.to_string(), b.to_string())).unwrap_or_default();

    Ok(Page(ComparePage { shell, repo: rs, cmp, files, ignore_ws, base_spec, head_spec, bookmarks, tags, propose }))

}