//! 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 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 }))

}

/// 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,

}

/// `/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;

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

}