//! Coverage reports (oxygenhub#113): Coveralls built into the hub. An
//! OxygenFlow job that declares an artifact named `coverage` in LCOV
//! format (what `cargo llvm-cov --lcov`, Istanbul, coverage.py and
//! gcov/lcov write) or Cobertura XML has it parsed when it is uploaded. The totals and each
//! file's counts are kept per run; the per-line counts are read again from
//! the artifact's blob for the file view. Paths are taken relative to the
//! job's workspace (`/src`), and only files of the run's state are kept.

use crate::db::{now_ms, Pool};
use crate::Shared;
use std::collections::{BTreeMap, HashSet};
use std::sync::Mutex;

/// The artifact name a pipeline gives its report.
pub const ARTIFACT: &str = "coverage";
/// The largest report parsed.
pub const MAX_REPORT: usize = 64 << 20;

/// One file's coverage, from a report.
#[derive(Clone, Debug, Default, PartialEq, Eq)]
pub struct FileCoverage {
    /// Relative to the repository's root.
    pub path: String,
    /// Each instrumented line and how often it ran, by line number.
    pub lines: BTreeMap<u32, u64>,
    pub functions_found: u64,
    pub functions_hit: u64,
    pub branches_found: u64,
    pub branches_hit: u64,
    /// The file's own `LF`/`LH` totals, when it had one record: the tool's
    /// own count, which can name lines the `DA` lines leave out (llvm-cov
    /// does), so the hub agrees with what the tool printed.
    pub declared_lines: Option<(u64, u64)>,
}

impl FileCoverage {
    pub fn lines_found(&self) -> u64 {
        self.declared_lines.map(|d| d.0).unwrap_or(self.lines.len() as u64)
    }

    pub fn lines_hit(&self) -> u64 {
        self.declared_lines.map(|d| d.1).unwrap_or_else(|| self.lines.values().filter(|n| **n > 0).count() as u64)
    }

    /// Every run of every line, added up.
    pub fn hits(&self) -> u64 {
        self.lines.values().fold(0u64, |a, n| a.saturating_add(*n))
    }
}

/// A path as a report names it, relative to the repository: the Flow
/// workspace's `/src/` and a leading `./` taken off. `None` for a path
/// outside the repository.
pub fn relative(path: &str) -> Option<String> {
    let p = path.trim();
    let p = p.strip_prefix("/src/").unwrap_or(p);
    let p = p.strip_prefix("./").unwrap_or(p);
    if p.is_empty() || p.starts_with('/') || p.contains('\\') || p.split('/').any(|s| s.is_empty() || s == "." || s == "..") {
        return None;
    }
    Some(p.to_string())
}

#[derive(Default)]
struct Acc {
    lines: BTreeMap<u32, u64>,
    functions: BTreeMap<String, u64>,
    branches: BTreeMap<(u32, String, String), u64>,
    declared_fn: (u64, u64),
    declared_br: (u64, u64),
    declared_lines: (Option<u64>, Option<u64>),
    records: u32,
}

/// Parse an LCOV report into each file's coverage, records for the same
/// file (from several test binaries) added together. Files whose paths
/// are outside the repository are counted in the second value.
pub fn parse_lcov(text: &str) -> Result<(Vec<FileCoverage>, usize), String> {
    let mut files: BTreeMap<String, Acc> = BTreeMap::new();
    let mut current: Option<Option<String>> = None;
    let mut outside = HashSet::new();
    let mut records = 0usize;
    // A new SF: record has begun and not yet been counted for its file.
    let mut started = false;
    let num = |s: &str| s.trim().parse::<u64>().unwrap_or(0);
    for line in text.lines() {
        let line = line.trim();
        if let Some(path) = line.strip_prefix("SF:") {
            records += 1;
            let rel = relative(path);
            if rel.is_none() {
                outside.insert(path.to_string());
            }
            current = Some(rel);
            started = true;
            continue;
        }
        if line == "end_of_record" {
            current = None;
            continue;
        }
        let Some(Some(path)) = &current else { continue };
        let acc = files.entry(path.clone()).or_default();
        if line == "TN:" || line.starts_with("TN:") {
            continue;
        }
        if std::mem::take(&mut started) {
            acc.records += 1;
        }
        if let Some(n) = line.strip_prefix("LF:") {
            acc.declared_lines.0 = Some(num(n));
        } else if let Some(n) = line.strip_prefix("LH:") {
            acc.declared_lines.1 = Some(num(n));
        } else if let Some(rest) = line.strip_prefix("DA:") {
            let mut parts = rest.split(',');
            if let (Some(l), Some(n)) = (parts.next(), parts.next()) {
                if let Ok(l) = l.trim().parse::<u32>() {
                    *acc.lines.entry(l).or_default() += num(n);
                }
            }
        } else if let Some(rest) = line.strip_prefix("FN:") {
            if let Some((_, name)) = rest.split_once(',') {
                acc.functions.entry(name.to_string()).or_default();
            }
        } else if let Some(rest) = line.strip_prefix("FNDA:") {
            if let Some((n, name)) = rest.split_once(',') {
                *acc.functions.entry(name.to_string()).or_default() += num(n);
            }
        } else if let Some(rest) = line.strip_prefix("BRDA:") {
            let parts: Vec<&str> = rest.split(',').collect();
            if let [l, block, branch, taken] = parts[..] {
                if let Ok(l) = l.trim().parse::<u32>() {
                    let taken = if taken.trim() == "-" { 0 } else { num(taken) };
                    *acc.branches.entry((l, block.to_string(), branch.to_string())).or_default() += taken;
                }
            }
        } else if let Some(n) = line.strip_prefix("FNF:") {
            acc.declared_fn.0 = acc.declared_fn.0.max(num(n));
        } else if let Some(n) = line.strip_prefix("FNH:") {
            acc.declared_fn.1 = acc.declared_fn.1.max(num(n));
        } else if let Some(n) = line.strip_prefix("BRF:") {
            acc.declared_br.0 = acc.declared_br.0.max(num(n));
        } else if let Some(n) = line.strip_prefix("BRH:") {
            acc.declared_br.1 = acc.declared_br.1.max(num(n));
        }
    }
    if records == 0 {
        return Err("this is not an LCOV report: it names no source file (no SF: line)".into());
    }
    let out = files
        .into_iter()
        .map(|(path, a)| {
            let (functions_found, functions_hit) = if a.functions.is_empty() {
                a.declared_fn
            } else {
                (a.functions.len() as u64, a.functions.values().filter(|n| **n > 0).count() as u64)
            };
            let (branches_found, branches_hit) = if a.branches.is_empty() {
                a.declared_br
            } else {
                (a.branches.len() as u64, a.branches.values().filter(|n| **n > 0).count() as u64)
            };
            let declared_lines = match (a.records, a.declared_lines) {
                (1, (Some(f), Some(h))) if h <= f && f >= a.lines.len() as u64 => Some((f, h)),
                _ => None,
            };
            FileCoverage { path, lines: a.lines, functions_found, functions_hit, branches_found, branches_hit, declared_lines }
        })
        .collect();
    Ok((out, outside.len()))
}

/// Parse a report in either format the hub reads: Cobertura XML (it
/// starts with `<`) or LCOV. Returns the files, those outside the
/// repository, and the format's name.
pub fn parse(text: &str) -> Result<(Vec<FileCoverage>, usize, &'static str), String> {
    if text.trim_start().starts_with('<') {
        parse_cobertura(text).map(|(f, o)| (f, o, "cobertura"))
    } else {
        parse_lcov(text).map(|(f, o)| (f, o, "lcov"))
    }
}

fn xml_attr(e: &quick_xml::events::BytesStart, name: &str) -> String {
    e.try_get_attribute(name)
        .ok()
        .flatten()
        .and_then(|a| a.normalized_value(quick_xml::XmlVersion::Implicit1_0).ok().map(|v| v.into_owned()))
        .unwrap_or_default()
}

/// Parse a Cobertura XML report (coverage.py `coverage xml`, JaCoCo via
/// cover2cover, .NET Coverlet, `cargo llvm-cov --cobertura`): each
/// `<class>`'s `<line number hits>` by file, with `branch` lines'
/// `condition-coverage="50% (1/2)"` as branches and `<method>`s as
/// functions (one is hit when any of its lines ran). A file named by
/// several classes is added together. A `<source>` is tried as the base of
/// a relative filename, the workspace's `/src` among them.
pub fn parse_cobertura(text: &str) -> Result<(Vec<FileCoverage>, usize), String> {
    use quick_xml::events::Event;
    let mut r = quick_xml::Reader::from_str(text);
    let mut sources: Vec<String> = Vec::new();
    let mut in_source = false;
    let mut source_text = String::new();
    // Files as the classes name them, resolved once the sources are known.
    let mut raw: BTreeMap<String, Acc> = BTreeMap::new();
    let mut file: Option<String> = None;
    let mut method: Option<(String, bool)> = None;
    let mut seen_root = false;
    loop {
        let ev = r.read_event().map_err(|e| format!("this is not a Cobertura report: {e}"))?;
        match ev {
            Event::Start(ref e) | Event::Empty(ref e) => {
                let tag = e.local_name().as_ref().to_string();
                match tag.as_str() {
                    "coverage" => seen_root = true,
                    "source" if matches!(ev, Event::Start(_)) => {
                        in_source = true;
                        source_text.clear();
                    }
                    "class" => {
                        let f = xml_attr(e, "filename");
                        raw.entry(f.clone()).or_default().records += 1;
                        file = Some(f);
                    }
                    "method" => method = Some((xml_attr(e, "name") + &xml_attr(e, "signature"), false)),
                    "line" => {
                        let Some(f) = &file else { continue };
                        let Ok(n) = xml_attr(e, "number").trim().parse::<u32>() else { continue };
                        let hits = xml_attr(e, "hits").trim().parse::<u64>().unwrap_or(0);
                        if let Some((_, hit)) = &mut method {
                            *hit |= hits > 0;
                            // A method's lines repeat the class's; count them once.
                            continue;
                        }
                        let acc = raw.entry(f.clone()).or_default();
                        *acc.lines.entry(n).or_default() += hits;
                        if xml_attr(e, "branch") == "true" {
                            // "50% (1/2)": covered of total conditions.
                            let cc = xml_attr(e, "condition-coverage");
                            if let Some((hit, total)) = cc
                                .split_once('(')
                                .and_then(|(_, rest)| rest.trim_end_matches(')').split_once('/'))
                                .and_then(|(h, t)| Some((h.trim().parse::<u64>().ok()?, t.trim().parse::<u64>().ok()?)))
                            {
                                for i in 0..total {
                                    let b = acc.branches.entry((n, "0".into(), i.to_string())).or_default();
                                    *b = (*b).max(u64::from(i < hit));
                                }
                            }
                        }
                    }
                    _ => {}
                }
                if matches!(ev, Event::Empty(_)) && tag == "method" {
                    if let (Some(f), Some((name, hit))) = (&file, method.take()) {
                        *raw.entry(f.clone()).or_default().functions.entry(name).or_default() += u64::from(hit);
                    }
                }
            }
            Event::Text(t) if in_source => source_text.push_str(&t.xml10_content()),
            Event::End(e) => match e.local_name().as_ref() {
                "source" => {
                    in_source = false;
                    sources.push(source_text.trim().trim_end_matches('/').to_string());
                }
                "class" => file = None,
                "method" => {
                    if let (Some(f), Some((name, hit))) = (&file, method.take()) {
                        *raw.entry(f.clone()).or_default().functions.entry(name).or_default() += u64::from(hit);
                    }
                }
                _ => {}
            },
            Event::Eof => break,
            _ => {}
        }
    }
    if !seen_root {
        return Err("this is not a Cobertura report: no <coverage> element".into());
    }
    if raw.is_empty() {
        return Err("this Cobertura report names no source file (no <class filename>)".into());
    }
    // A filename relative to one of the sources, or to the workspace.
    let resolve = |f: &str| -> Option<String> {
        if f.starts_with('/') {
            return relative(f);
        }
        sources.iter().filter(|s| !s.is_empty() && *s != ".").find_map(|s| relative(&format!("{s}/{f}"))).or_else(|| relative(f))
    };
    let mut files: BTreeMap<String, Acc> = BTreeMap::new();
    let mut outside = HashSet::new();
    for (f, a) in raw {
        let Some(path) = resolve(&f) else {
            outside.insert(f);
            continue;
        };
        let into = files.entry(path).or_default();
        for (l, n) in a.lines {
            *into.lines.entry(l).or_default() += n;
        }
        for (k, n) in a.functions {
            *into.functions.entry(k).or_default() += n;
        }
        for (k, n) in a.branches {
            let b = into.branches.entry(k).or_default();
            *b = (*b).max(n);
        }
    }
    let out = files
        .into_iter()
        .map(|(path, a)| FileCoverage {
            path,
            functions_found: a.functions.len() as u64,
            functions_hit: a.functions.values().filter(|n| **n > 0).count() as u64,
            branches_found: a.branches.len() as u64,
            branches_hit: a.branches.values().filter(|n| **n > 0).count() as u64,
            lines: a.lines,
            declared_lines: None,
        })
        .collect();
    Ok((out, outside.len()))
}

/// A percentage to one decimal place, or none when nothing was counted.
pub fn percent(hit: i64, found: i64) -> Option<f64> {
    (found > 0).then(|| (hit as f64 * 1000.0 / found as f64).round() / 10.0)
}

#[derive(Clone, Debug, sqlx::FromRow)]
pub struct Report {
    pub id: i64,
    pub repo_id: i64,
    /// The Flow run and job it came from; none for an upload (#136).
    pub run_id: Option<i64>,
    pub job_id: Option<i64>,
    pub job: String,
    pub run_number: i64,
    pub bookmark: String,
    pub state: String,
    pub heads: String,
    pub blob: String,
    pub format: String,
    pub lines_found: i64,
    pub lines_hit: i64,
    pub functions_found: i64,
    pub functions_hit: i64,
    pub branches_found: i64,
    pub branches_hit: i64,
    pub hits: i64,
    pub files: i64,
    pub dropped: i64,
    pub created_ms: i64,
    /// Who uploaded it from a workstation (#136); empty for a job's report.
    pub uploader: String,
}

impl Report {
    /// Whether it was uploaded rather than measured by a Flow job.
    pub fn uploaded(&self) -> bool {
        !self.uploader.is_empty()
    }

    /// Where its figure came from: "run #61", or "uploaded by NAME".
    pub fn source(&self) -> String {
        if self.uploaded() {
            format!("uploaded by {}", self.uploader)
        } else {
            format!("run #{}", self.run_number)
        }
    }

    /// How often an instrumented line ran, on average.
    pub fn hits_per_line(&self) -> Option<f64> {
        (self.lines_found > 0).then(|| self.hits as f64 / self.lines_found as f64)
    }

    pub fn percent(&self) -> Option<f64> {
        percent(self.lines_hit, self.lines_found)
    }

    pub fn functions_percent(&self) -> Option<f64> {
        percent(self.functions_hit, self.functions_found)
    }

    pub fn branches_percent(&self) -> Option<f64> {
        percent(self.branches_hit, self.branches_found)
    }

    pub fn head_list(&self) -> Vec<&str> {
        self.heads.split(',').filter(|h| !h.is_empty()).collect()
    }
}

#[derive(Clone, Debug, sqlx::FromRow)]
pub struct FileRow {
    pub report_id: i64,
    pub path: String,
    pub lines_found: i64,
    pub lines_hit: i64,
    pub functions_found: i64,
    pub functions_hit: i64,
    pub branches_found: i64,
    pub branches_hit: i64,
}

impl FileRow {
    pub fn percent(&self) -> Option<f64> {
        percent(self.lines_hit, self.lines_found)
    }

    pub fn missed(&self) -> i64 {
        self.lines_found - self.lines_hit
    }
}

/// Repositories with a report, so their pages show the Coverage tab:
/// keyed by the hub's repository root and the id, unique even between
/// hubs in one process.
static HAS: Mutex<Option<HashSet<String>>> = Mutex::new(None);

fn key(app: &Shared, repo_id: i64) -> String {
    format!("{}#{repo_id}", app.repos.root().display())
}

pub fn has_reports(app: &Shared, repo_id: i64) -> bool {
    HAS.lock().unwrap_or_else(|p| p.into_inner()).as_ref().is_some_and(|s| s.contains(&key(app, repo_id)))
}

fn mark(app: &Shared, repo_id: i64) {
    HAS.lock().unwrap_or_else(|p| p.into_inner()).get_or_insert_with(HashSet::new).insert(key(app, repo_id));
}

/// At start: which repositories have reports.
pub async fn load(app: &Shared) -> sqlx::Result<()> {
    let ids: Vec<(i64,)> = sqlx::query_as("SELECT DISTINCT repo_id FROM coverage_reports").fetch_all(&app.db).await?;
    for (id,) in ids {
        mark(app, id);
    }
    Ok(())
}

/// What a run's report is kept with.
pub struct Origin<'a> {
    pub repo_id: i64,
    /// The Flow run and job; none for an upload, which names its uploader.
    pub run_id: Option<i64>,
    pub run_number: i64,
    pub job_id: Option<i64>,
    pub uploader: &'a str,
    pub job: &'a str,
    pub bookmark: &'a str,
    pub state: &'a str,
    pub heads: &'a [String],
    pub blob: &'a str,
    /// `lcov` or `cobertura`.
    pub format: &'a str,
}

/// Keep a parsed report: the files outside `in_state` are dropped and
/// counted. Replaces an earlier report of the same job.
pub async fn keep(app: &Shared, o: &Origin<'_>, files: Vec<FileCoverage>, outside: usize, in_state: &HashSet<String>) -> sqlx::Result<i64> {
    let (kept, missing): (Vec<FileCoverage>, Vec<FileCoverage>) = files.into_iter().partition(|f| in_state.contains(&f.path));
    let sum = |f: &dyn Fn(&FileCoverage) -> u64| kept.iter().map(f).sum::<u64>() as i64;
    let mut tx = crate::db::begin_write(&app.db).await?;
    if let Some(job) = o.job_id {
        sqlx::query("DELETE FROM coverage_reports WHERE job_id = $1").bind(job).execute(&mut *tx).await?;
    }
    let id: i64 = sqlx::query_scalar(
        "INSERT INTO coverage_reports (repo_id, run_id, job_id, job, run_number, bookmark, state, heads, blob, format, \
         lines_found, lines_hit, functions_found, functions_hit, branches_found, branches_hit, hits, files, dropped, created_ms, uploader) \
         VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18, $19, $20, $21) RETURNING id",
    )
    .bind(o.repo_id)
    .bind(o.run_id)
    .bind(o.job_id)
    .bind(o.job)
    .bind(o.run_number)
    .bind(o.bookmark)
    .bind(o.state)
    .bind(o.heads.join(","))
    .bind(o.blob)
    .bind(o.format)
    .bind(sum(&|f| f.lines_found()))
    .bind(sum(&|f| f.lines_hit()))
    .bind(sum(&|f| f.functions_found))
    .bind(sum(&|f| f.functions_hit))
    .bind(sum(&|f| f.branches_found))
    .bind(sum(&|f| f.branches_hit))
    .bind(kept.iter().fold(0u64, |a, f| a.saturating_add(f.hits())).min(i64::MAX as u64) as i64)
    .bind(kept.len() as i64)
    .bind((missing.len() + outside) as i64)
    .bind(now_ms())
    .bind(o.uploader)
    .fetch_one(&mut *tx)
    .await?;
    for f in &kept {
        sqlx::query(
            "INSERT INTO coverage_files (report_id, path, lines_found, lines_hit, functions_found, functions_hit, branches_found, branches_hit) \
             VALUES ($1, $2, $3, $4, $5, $6, $7, $8)",
        )
        .bind(id)
        .bind(&f.path)
        .bind(f.lines_found() as i64)
        .bind(f.lines_hit() as i64)
        .bind(f.functions_found as i64)
        .bind(f.functions_hit as i64)
        .bind(f.branches_found as i64)
        .bind(f.branches_hit as i64)
        .execute(&mut *tx)
        .await?;
    }
    tx.commit().await?;
    mark(app, o.repo_id);
    Ok(id)
}

pub async fn report(pool: &Pool, repo_id: i64, id: i64) -> sqlx::Result<Option<Report>> {
    sqlx::query_as("SELECT * FROM coverage_reports WHERE id = $1 AND repo_id = $2").bind(id).bind(repo_id).fetch_optional(pool).await
}

/// The newest reports on a bookmark, newest first.
pub async fn on_bookmark(pool: &Pool, repo_id: i64, bookmark: &str, limit: i64) -> sqlx::Result<Vec<Report>> {
    sqlx::query_as("SELECT * FROM coverage_reports WHERE repo_id = $1 AND bookmark = $2 ORDER BY created_ms DESC, id DESC LIMIT $3")
        .bind(repo_id)
        .bind(bookmark)
        .bind(limit)
        .fetch_all(pool)
        .await
}

/// When the repository's first report on any bookmark was kept.
pub async fn first_ms(pool: &Pool, repo_id: i64) -> sqlx::Result<Option<i64>> {
    sqlx::query_scalar("SELECT MIN(created_ms) FROM coverage_reports WHERE repo_id = $1").bind(repo_id).fetch_one(pool).await
}

/// The bookmarks with reports, the most recent first.
pub async fn bookmarks(pool: &Pool, repo_id: i64) -> sqlx::Result<Vec<String>> {
    sqlx::query_scalar("SELECT bookmark FROM coverage_reports WHERE repo_id = $1 GROUP BY bookmark ORDER BY MAX(created_ms) DESC")
        .bind(repo_id)
        .fetch_all(pool)
        .await
}

/// A repository's coverage rules.
#[derive(Clone, Copy, Debug, Default, PartialEq)]
pub struct Rules {
    /// The check fails below this percentage.
    pub min: Option<f64>,
    /// The check fails when coverage falls more than this many points.
    pub max_drop: Option<f64>,
}

pub async fn rules(pool: &Pool, repo_id: i64) -> sqlx::Result<Rules> {
    let row: Option<(Option<f64>, Option<f64>)> =
        sqlx::query_as("SELECT min, max_drop FROM coverage_settings WHERE repo_id = $1").bind(repo_id).fetch_optional(pool).await?;
    Ok(row.map(|(min, max_drop)| Rules { min, max_drop }).unwrap_or_default())
}

pub async fn set_rules(pool: &Pool, repo_id: i64, r: Rules) -> sqlx::Result<()> {
    sqlx::query(
        "INSERT INTO coverage_settings (repo_id, min, max_drop) VALUES ($1, $2, $3) \
         ON CONFLICT (repo_id) DO UPDATE SET min = excluded.min, max_drop = excluded.max_drop",
    )
    .bind(repo_id)
    .bind(r.min)
    .bind(r.max_drop)
    .execute(pool)
    .await?;
    Ok(())
}

/// What a report is measured against: on the default bookmark, the report
/// before it there; on any other, the default bookmark's latest before it.
pub async fn baseline(pool: &Pool, r: &Report, default_bookmark: &str) -> sqlx::Result<Option<Report>> {
    sqlx::query_as(
        "SELECT * FROM coverage_reports WHERE repo_id = $1 AND bookmark = $2 AND id <> $3 AND (created_ms < $4 OR (created_ms = $5 AND id < $6)) \
         ORDER BY created_ms DESC, id DESC LIMIT 1",
    )
    .bind(r.repo_id)
    .bind(default_bookmark)
    .bind(r.id)
    .bind(r.created_ms)
    .bind(r.created_ms)
    .bind(r.id)
    .fetch_optional(pool)
    .await
}

/// The `coverage` check for a report: passed or failed, and what to say.
pub fn verdict(r: &Report, base: Option<&Report>, base_name: &str, rules: Rules) -> (&'static str, String) {
    let Some(p) = r.percent() else { return ("passed", "no instrumented lines".into()) };
    let delta = base.and_then(|b| Some(p - b.percent()?));
    let against = match delta {
        Some(d) if d.abs() < 0.05 => format!(", unchanged against {base_name}"),
        Some(d) => format!(" ({d:+.1} against {base_name})"),
        None => String::new(),
    };
    if let Some(min) = rules.min.filter(|m| p < *m) {
        return ("failed", format!("{p:.1}%{against}: below the minimum of {min}%"));
    }
    if let (Some(max), Some(d)) = (rules.max_drop, delta) {
        if d < -max {
            return ("failed", format!("{p:.1}%{against}: falls more than the {max} points allowed"));
        }
    }
    ("passed", format!("{p:.1}%{against}"))
}

pub async fn for_run(pool: &Pool, run_id: i64) -> sqlx::Result<Vec<Report>> {
    sqlx::query_as("SELECT * FROM coverage_reports WHERE run_id = $1 ORDER BY job").bind(run_id).fetch_all(pool).await
}

pub async fn files(pool: &Pool, report_id: i64) -> sqlx::Result<Vec<FileRow>> {
    sqlx::query_as("SELECT * FROM coverage_files WHERE report_id = $1 ORDER BY path").bind(report_id).fetch_all(pool).await
}

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

    const LCOV: &str = "TN:\nSF:/src/crates/a/src/lib.rs\nFN:3,alpha\nFN:9,beta\nFNDA:4,alpha\nFNDA:0,beta\nFNF:2\nFNH:1\n\
DA:3,4\nDA:4,4\nDA:9,0\nDA:10,0\nBRDA:4,0,0,3\nBRDA:4,0,1,-\nBRF:2\nBRH:1\nLF:4\nLH:2\nend_of_record\n\
SF:/src/crates/a/src/lib.rs\nDA:9,1\nend_of_record\n\
SF:./README.md\nDA:1,1\nend_of_record\n\
SF:/home/runner/.cargo/registry/src/dep/lib.rs\nDA:1,1\nend_of_record\n";

    #[test]
    fn lcov_reports_are_read_and_merged() {
        let (files, outside) = parse_lcov(LCOV).unwrap();
        assert_eq!(outside, 1, "the dependency outside the workspace");
        assert_eq!(files.len(), 2);
        let lib = &files[1];
        assert_eq!(lib.path, "crates/a/src/lib.rs");
        assert_eq!(lib.lines, [(3, 4), (4, 4), (9, 1), (10, 0)].into_iter().collect());
        assert_eq!((lib.lines_found(), lib.lines_hit()), (4, 3), "the second record ran line 9");
        assert_eq!((lib.functions_found, lib.functions_hit), (2, 1));
        assert_eq!((lib.branches_found, lib.branches_hit), (2, 1));
        assert_eq!(files[0].path, "README.md");
        assert_eq!(lib.declared_lines, None, "two records: counted from the lines");
        // One record whose totals name lines its DA lines leave out, as llvm-cov writes.
        let (one, _) = parse_lcov("SF:/src/a.rs\nDA:1,1\nDA:2,0\nLF:5\nLH:3\nend_of_record\n").unwrap();
        assert_eq!((one[0].lines_found(), one[0].lines_hit()), (5, 3));
        assert!(parse_lcov("not a report\n").unwrap_err().contains("not an LCOV report"));
    }

    #[test]
    fn the_check_follows_the_rules() {
        let report = |pct_hit: i64| Report {
            id: 2,
            repo_id: 1,
            run_id: Some(1),
            job_id: Some(1),
            job: "test".into(),
            run_number: 1,
            bookmark: "feature".into(),
            state: String::new(),
            heads: String::new(),
            blob: String::new(),
            format: "lcov".into(),
            lines_found: 1000,
            lines_hit: pct_hit,
            functions_found: 0,
            functions_hit: 0,
            branches_found: 0,
            branches_hit: 0,
            hits: 0,
            files: 1,
            dropped: 0,
            created_ms: 0,
            uploader: String::new(),
        };
        let (now, before) = (report(819), report(822));
        let none = Rules::default();
        assert_eq!(verdict(&now, Some(&before), "main", none), ("passed", "81.9% (-0.3 against main)".to_string()));
        assert_eq!(verdict(&now, None, "main", none), ("passed", "81.9%".to_string()));
        assert_eq!(verdict(&now, Some(&now), "main", none).1, "81.9%, unchanged against main");
        let strict = Rules { min: Some(85.0), max_drop: None };
        assert_eq!(
            verdict(&now, Some(&before), "main", strict),
            ("failed", "81.9% (-0.3 against main): below the minimum of 85%".to_string())
        );
        let drop = Rules { min: None, max_drop: Some(0.2) };
        assert_eq!(verdict(&now, Some(&before), "main", drop).0, "failed");
        assert_eq!(verdict(&now, Some(&before), "main", Rules { min: None, max_drop: Some(0.5) }).0, "passed");
    }

    #[test]
    fn paths_are_taken_relative_to_the_workspace() {
        assert_eq!(relative("/src/a/b.rs").as_deref(), Some("a/b.rs"));
        assert_eq!(relative("./a/b.rs").as_deref(), Some("a/b.rs"));
        assert_eq!(relative("a/b.rs").as_deref(), Some("a/b.rs"));
        for bad in ["/etc/passwd", "a/../b", "", "/src/", "a//b", "C:\\x\\y.rs"] {
            assert_eq!(relative(bad), None, "{bad}");
        }
        assert_eq!(percent(1, 3), Some(33.3));
        assert_eq!(percent(0, 0), None);
    }

    #[test]
    fn cobertura_from_coverage_py_and_coverlet() {
        // coverage.py: a source to resolve against, branches by condition.
        let py = r#"<?xml version="1.0" ?>
<coverage version="7.4" line-rate="0.6" branch-rate="0.5">
  <sources><source>/src/app</source></sources>
  <packages><package name="app"><classes>
    <class name="main.py" filename="main.py" line-rate="0.66">
      <methods/>
      <lines>
        <line number="1" hits="1"/>
        <line number="2" hits="0"/>
        <line number="3" hits="4" branch="true" condition-coverage="50% (1/2)"/>
      </lines>
    </class>
    <class name="gone.py" filename="/usr/lib/python3/x.py"><lines><line number="1" hits="1"/></lines></class>
  </classes></package></packages>
</coverage>"#;
        let (files, outside, format) = parse(py).unwrap();
        assert_eq!((format, outside), ("cobertura", 1));
        let f = &files[0];
        assert_eq!(f.path, "app/main.py");
        assert_eq!((f.lines_found(), f.lines_hit(), f.hits()), (3, 2, 5));
        assert_eq!((f.branches_found, f.branches_hit), (2, 1));

        // Coverlet: methods with their own lines, two classes in one file.
        let net = r#"<coverage><sources><source>/src/</source></sources><packages><package name="Lib"><classes>
<class name="Lib.A" filename="Lib/A.cs"><methods><method name="Run" signature="()"><lines><line number="5" hits="2"/></lines></method><method name="Idle" signature="()"><lines><line number="9" hits="0"/></lines></method></methods>
<lines><line number="5" hits="2"/><line number="9" hits="0"/></lines></class>
<class name="Lib.A/Inner" filename="Lib/A.cs"><methods/><lines><line number="12" hits="1"/></lines></class>
</classes></package></packages></coverage>"#;
        let (files, _, _) = parse(net).unwrap();
        let f = &files[0];
        assert_eq!(f.path, "Lib/A.cs");
        assert_eq!((f.lines_found(), f.lines_hit()), (3, 2));
        assert_eq!((f.functions_found, f.functions_hit), (2, 1));

        assert!(parse("<html/>").unwrap_err().contains("Cobertura"));
        assert_eq!(parse("SF:/src/a.rs\nDA:1,1\nend_of_record\n").unwrap().2, "lcov");
    }
}