//! Findings, the run report, and the emitter checks report through.
//!
//! The emitter is deliberately thin: checks name a tag and give a message;
//! metadata, output letter and explanations come from the registry, so
//! findings from the native engine and findings parsed from the wrapped
//! lintian share one shape and one rendering path.

use crate::lint::check;
use crate::lint::tag::Tag;

/// Where a finding comes from.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Origin {
    /// Emitted by pkh's native Rust checks.
    Native,
    /// Parsed from the wrapped lintian's output.
    Lintian,
}

/// One lint finding, whatever produced it.
#[derive(Debug, Clone)]
pub struct Finding {
    /// Output letter (`E`, `W`, `I`, `P`, `X`, `O`, `C`): severity for
    /// native findings, verbatim from the output line in wrapper mode.
    pub letter: char,
    /// Stable tag name (`missing-debian-copyright-file`).
    pub tag_name: String,
    /// Free-form details after the tag name; empty when the tag stands alone.
    pub message: String,
    /// Package the finding belongs to (`hello`).
    pub package: String,
    /// Processable type lintian displays after the package name (`source`,
    /// `changes`, ...); None for binary findings, which lintian prints
    /// without a type.
    pub processable_type: Option<String>,
    /// Explanation lines shown by `--info`: the `N:` blocks lintian attaches
    /// to the finding in wrapper mode, or the native tag's description and
    /// references.
    pub explanation: Vec<String>,
    /// Native or parsed-from-lintian.
    pub origin: Origin,
}

impl Finding {
    /// Lowercase severity/classification name for this finding's letter, as
    /// used in `--fail-on` values and JSON output.
    pub fn severity_name(&self) -> &'static str {
        match self.letter {
            'E' => "error",
            'W' => "warning",
            'I' => "info",
            'P' => "pedantic",
            'X' => "experimental",
            'O' => "overridden",
            _ => "classification",
        }
    }
}

/// The full result of one lint run: every finding, from every source.
pub struct LintReport {
    /// All findings in emission order: the wrapper's first, then the native
    /// ones (deduplicated by tag name against the wrapper's).
    pub findings: Vec<Finding>,
    /// Display name of the linted source package.
    pub source_name: String,
    /// The wrapper was skipped because lintian is not installed; the
    /// renderer prints a notice and the run is native-only.
    pub wrapper_unavailable: bool,
    /// Run-level notes (`N:` lines): how the linted artifact was obtained,
    /// and similar context that is not a finding.
    pub notes: Vec<String>,
}

/// Sink checks report findings through. Resolves tag metadata from the
/// registry so checks only ever name the tag they mean.
pub struct Emitter<'a> {
    package: String,
    findings: &'a mut Vec<Finding>,
}

impl<'a> Emitter<'a> {
    /// Emitter for findings of `package` (e.g. the source package name),
    /// appending into `findings`.
    pub fn new(package: String, findings: &'a mut Vec<Finding>) -> Emitter<'a> {
        Emitter { package, findings }
    }

    /// Emit `tag_name` with `message` as its detail line. Native findings
    /// always report on the source package; an unknown tag name (a registry
    /// bug) still produces a finding rather than panicking — the registry
    /// test makes that path unreachable in practice.
    pub fn tag(&mut self, tag_name: &str, message: impl Into<String>) {
        let (letter, explanation) = match check::find_tag(tag_name) {
            Some(tag) => (tag.letter(), explanation_of(tag)),
            None => ('E', Vec::new()),
        };
        self.findings.push(Finding {
            letter,
            tag_name: tag_name.to_string(),
            message: message.into(),
            package: self.package.clone(),
            processable_type: Some("source".to_string()),
            explanation,
            origin: Origin::Native,
        });
    }
}

/// The explanation `--info` shows for a native tag: its description plus any
/// references, prefixed like lintian's "Please refer to" pointers.
fn explanation_of(tag: &Tag) -> Vec<String> {
    let mut lines = vec![tag.description.to_string()];
    for reference in tag.references {
        lines.push(format!("Please refer to {}", reference));
    }
    lines
}