//! `pkh lint`: lint a Debian source tree, with lintian feature parity.
//!
//! The strategy is *wrap first, port second*: the
//! [wrapper](wrapper) runs the installed lintian over an ephemeral source
//! package for day-one parity with every lintian check, while the native
//! engine (check registry, collectors, emitter) hosts pkh-specific workflow
//! checks (`pkh-*` tags) and grows ported lintian checks incrementally.
//! Both findings merge into one report — deduplicated by tag name, which is
//! why native checks mirror lintian's tag names for equivalent checks —
//! rendered as lintian-shaped text or JSON, with lintian's exit-code
//! contract (0 clean, 1 findings at/above `--fail-on`, 2 runtime error).

pub mod check;
pub mod checks;
pub mod collect;
pub mod emit;
pub mod output;
pub mod tag;
pub mod wrapper;

use std::collections::HashSet;
use std::path::PathBuf;

use crate::lint::check::Check;
use crate::lint::collect::LintData;
use crate::lint::emit::{Finding, LintReport};

/// Knobs of one `pkh lint` run, built from the CLI in `main.rs`.
pub struct LintOptions {
    /// Source tree to lint.
    pub path: PathBuf,
    /// Run the native engine only; never invoke the lintian wrapper.
    pub native: bool,
    /// Levels that make the exit code 1 (`--fail-on`, default: error).
    pub fail_on: Vec<output::Level>,
    /// Show tag explanations under each finding (`--info`, lintian's `-i`).
    pub info: bool,
    /// Also display info-level (`I:`) findings (lintian's `-I`).
    pub display_info: bool,
    /// Also display pedantic (`P:`) findings.
    pub pedantic: bool,
    /// Also display experimental (`X:`) findings.
    pub experimental: bool,
    /// Also display overridden (`O:`) findings.
    pub show_overrides: bool,
    /// Tag names to ignore for this run.
    pub suppress_tags: Vec<String>,
    /// Run only these native checks (`--check`, repeatable).
    pub only_checks: Vec<String>,
    /// Ignore any existing `pkh build` output and pack the tree fresh.
    pub repack: bool,
    /// Emit JSON instead of text.
    pub json: bool,
    /// Text colorization mode (`--color`, default auto: TTY without NO_COLOR).
    pub color: output::ColorMode,
    /// Target distribution (debian/ubuntu), when known.
    pub dist: Option<String>,
    /// Target series, when known.
    pub series: Option<String>,
}

/// Run one lint: collect package information, run the native checks, wrap
/// lintian (unless `--native`), and merge everything into one report.
pub fn run(options: &LintOptions) -> Result<LintReport, String> {
    let data = LintData::collect(
        &options.path,
        options.dist.as_deref(),
        options.series.as_deref(),
    );
    let mut report = LintReport {
        findings: Vec::new(),
        source_name: data.source_name.clone(),
        wrapper_unavailable: false,
        notes: Vec::new(),
    };

    if !options.native {
        match wrapper::run(&data.root, options)? {
            Some(outcome) => {
                report.findings.extend(outcome.findings);
                report.notes = outcome.notes;
            }
            None => report.wrapper_unavailable = true,
        }
    }

    let selected: Vec<&'static dyn Check> = if options.only_checks.is_empty() {
        check::CHECKS.to_vec()
    } else {
        options
            .only_checks
            .iter()
            .map(|id| check::find_check(id).ok_or_else(|| format!("Unknown --check '{id}'")))
            .collect::<Result<_, _>>()?
    };

    let mut native = Vec::new();
    {
        let mut emitter = emit::Emitter::new(report.source_name.clone(), &mut native);
        for check in selected {
            check.run(&data, &mut emitter);
        }
    }
    report.findings.extend(merge(&report.findings, native));

    if !options.suppress_tags.is_empty() {
        report
            .findings
            .retain(|finding| !options.suppress_tags.contains(&finding.tag_name));
    }
    Ok(report)
}

/// Append `native` findings to `lintian`'s, dropping native duplicates by
/// tag name (the wrapper's verdict wins for tags both engines produce).
fn merge(lintian: &[Finding], native: Vec<Finding>) -> Vec<Finding> {
    let known: HashSet<&str> = lintian.iter().map(|f| f.tag_name.as_str()).collect();
    native
        .into_iter()
        .filter(|finding| !known.contains(finding.tag_name.as_str()))
        .collect()
}

/// The `--list-tags` catalog: one line per registered native tag.
pub fn list_tags() -> String {
    let mut out = String::new();
    for check in check::CHECKS {
        for tag in check.tags() {
            out.push_str(&format!(
                "{} [{}] {}\n  {}\n",
                tag.letter(),
                check.id(),
                tag.name,
                tag.description
            ));
        }
    }
    out
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::lint::emit::Origin;

    fn finding(tag: &str, origin: Origin) -> Finding {
        Finding {
            letter: 'W',
            tag_name: tag.to_string(),
            message: String::new(),
            package: "hello".to_string(),
            processable_type: Some("source".to_string()),
            explanation: Vec::new(),
            origin,
        }
    }

    #[test]
    fn merge_drops_native_duplicates_by_tag_name() {
        let lintian = vec![finding("no-debian-copyright-in-source", Origin::Lintian)];
        let native = vec![
            finding("no-debian-copyright-in-source", Origin::Native),
            finding("pkh-debian-changes-not-committed", Origin::Native),
        ];
        let merged = merge(&lintian, native);
        assert_eq!(merged.len(), 1);
        assert_eq!(merged[0].tag_name, "pkh-debian-changes-not-committed");
        assert_eq!(merged[0].origin, Origin::Native);
    }

    #[test]
    fn native_tags_resolve_from_the_registry() {
        let tag = check::find_tag("pkh-debian-changes-not-committed")
            .expect("pkh check tags must resolve");
        assert_eq!(tag.letter(), 'W');
    }

    #[test]
    fn unknown_native_tags_still_produce_findings() {
        let mut sink = Vec::new();
        let mut emitter = emit::Emitter::new("hello".to_string(), &mut sink);
        emitter.tag("no-such-tag-anywhere", "boom");
        assert_eq!(sink.len(), 1);
        assert_eq!(sink[0].tag_name, "no-such-tag-anywhere");
    }
}