elio 1.0.1

// This module is only compiled on Linux / BSD (gated in discovery/mod.rs).

use std::path::{Path, PathBuf};
use std::process::Command;

use crate::preview::process::run_command_capture_stdout_cancellable;

pub(super) fn detect_mime_type(path: &Path, canceled: &impl Fn() -> bool) -> Option<String> {
    // Fast path: look up the file extension in the XDG MIME globs database.
    // This is instant (pure file read), covers virtually all files with a
    // recognisable extension, and works correctly on both Linux and BSD because
    // it searches the full XDG data dir chain rather than a hardcoded path.
    if let Some(mime) = mime_from_xdg_database(path) {
        return Some(mime);
    }

    if canceled() {
        return None;
    }

    // Slow path: invoke xdg-mime for extensionless or ambiguous files that
    // need content-based (magic-byte) detection.
    let mut cmd = Command::new("xdg-mime");
    cmd.args(["query", "filetype"]).arg(path);
    if let Some(out) = run_command_capture_stdout_cancellable(cmd, "open-with-mime", canceled) {
        let s = String::from_utf8_lossy(&out).trim().to_string();
        if !s.is_empty() {
            return Some(s);
        }
    }

    if canceled() {
        return None;
    }

    // Last resort: file(1).
    let mut cmd = Command::new("file");
    cmd.args(["--mime-type", "-b"]).arg(path);
    if let Some(out) = run_command_capture_stdout_cancellable(cmd, "open-with-mime-fb", canceled) {
        let s = String::from_utf8_lossy(&out).trim().to_string();
        if !s.is_empty() {
            return Some(s);
        }
    }

    None
}

/// Looks up MIME type from the XDG MIME globs database without spawning any
/// subprocess.  Searches each XDG data directory for `mime/globs2` (weighted)
/// and falls back to `mime/globs` (unweighted).
///
/// This correctly handles BSD systems where `shared-mime-info` installs to
/// `/usr/local/share/mime/` rather than `/usr/share/mime/`.
fn mime_from_xdg_database(path: &Path) -> Option<String> {
    mime_from_data_dirs(path, &super::xdg_data_dirs())
}

/// Inner implementation that accepts an explicit data-dir list for testing.
/// Searches `{dir}/mime/globs2` (highest weight wins across all dirs), then
/// `{dir}/mime/globs` (first match across dirs in priority order).
pub(super) fn mime_from_data_dirs(path: &Path, data_dirs: &[PathBuf]) -> Option<String> {
    let ext = path.extension()?.to_str()?.to_lowercase();
    let target = format!("*.{ext}");

    // ── globs2 pass: weight:mime/type:glob-pattern ────────────────────────────
    // Collect the highest-weight match across all data dirs.  This mirrors how
    // shared-mime-info merges databases from multiple XDG data directories.
    let mut best_weight = -1i32;
    let mut best_mime: Option<String> = None;

    for dir in data_dirs {
        let globs2 = dir.join("mime/globs2");
        let Ok(contents) = std::fs::read_to_string(&globs2) else {
            continue;
        };
        for line in contents.lines() {
            let line = line.trim();
            if line.starts_with('#') || line.is_empty() {
                continue;
            }
            let mut parts = line.splitn(3, ':');
            let (Some(w_str), Some(mime), Some(pattern)) =
                (parts.next(), parts.next(), parts.next())
            else {
                continue;
            };
            if pattern != target {
                continue;
            }
            let weight: i32 = w_str.parse().unwrap_or(50);
            if weight > best_weight {
                best_weight = weight;
                best_mime = Some(mime.to_string());
            }
        }
    }
    if best_mime.is_some() {
        return best_mime;
    }

    // ── globs pass: mime/type:glob-pattern ────────────────────────────────────
    // No weights — first match in priority order wins.
    for dir in data_dirs {
        let globs = dir.join("mime/globs");
        let Ok(contents) = std::fs::read_to_string(&globs) else {
            continue;
        };
        for line in contents.lines() {
            let line = line.trim();
            if line.starts_with('#') || line.is_empty() {
                continue;
            }
            let Some((mime, pattern)) = line.split_once(':') else {
                continue;
            };
            if pattern == target {
                return Some(mime.to_string());
            }
        }
    }

    None
}

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

    // ── helpers ───────────────────────────────────────────────────────────────

    fn unique_dir(label: &str) -> PathBuf {
        use std::time::{SystemTime, UNIX_EPOCH};
        let nanos = SystemTime::now()
            .duration_since(UNIX_EPOCH)
            .unwrap_or_default()
            .subsec_nanos();
        std::env::temp_dir().join(format!(
            "elio-mime-test-{label}-{}-{nanos}",
            std::process::id()
        ))
    }

    fn write_globs2(dir: &Path, content: &str) {
        let mime_dir = dir.join("mime");
        fs::create_dir_all(&mime_dir).expect("create mime dir");
        fs::write(mime_dir.join("globs2"), content).expect("write globs2");
    }

    fn write_globs(dir: &Path, content: &str) {
        let mime_dir = dir.join("mime");
        fs::create_dir_all(&mime_dir).expect("create mime dir");
        fs::write(mime_dir.join("globs"), content).expect("write globs");
    }

    // ── mime_from_data_dirs ───────────────────────────────────────────────────

    #[test]
    fn finds_mime_type_from_globs2() {
        let dir = unique_dir("globs2-basic");
        write_globs2(&dir, "50:text/markdown:*.md\n");

        let result = mime_from_data_dirs(Path::new("/any/file.md"), std::slice::from_ref(&dir));
        let _ = fs::remove_dir_all(&dir);

        assert_eq!(result.as_deref(), Some("text/markdown"));
    }

    #[test]
    fn falls_back_to_globs_when_globs2_absent() {
        let dir = unique_dir("globs-fallback");
        write_globs(&dir, "text/plain:*.txt\n");

        let result = mime_from_data_dirs(Path::new("/any/file.txt"), std::slice::from_ref(&dir));
        let _ = fs::remove_dir_all(&dir);

        assert_eq!(result.as_deref(), Some("text/plain"));
    }

    #[test]
    fn globs2_higher_weight_wins_over_lower_weight() {
        let dir = unique_dir("globs2-weight");
        // Two entries for *.md — higher weight (60) should win.
        write_globs2(
            &dir,
            "40:text/x-markdown:*.md\n\
             60:text/markdown:*.md\n\
             50:text/plain:*.txt\n",
        );

        let result = mime_from_data_dirs(Path::new("/docs/readme.md"), std::slice::from_ref(&dir));
        let _ = fs::remove_dir_all(&dir);

        assert_eq!(result.as_deref(), Some("text/markdown"));
    }

    #[test]
    fn globs2_weights_compared_across_multiple_data_dirs() {
        // dir1 has a low-weight match; dir2 has a higher-weight match.
        // The higher weight should win regardless of dir priority.
        let dir1 = unique_dir("multi-dir-low");
        let dir2 = unique_dir("multi-dir-high");
        write_globs2(&dir1, "30:text/x-markdown:*.md\n");
        write_globs2(&dir2, "70:text/markdown:*.md\n");

        let result =
            mime_from_data_dirs(Path::new("/docs/readme.md"), &[dir1.clone(), dir2.clone()]);
        let _ = fs::remove_dir_all(&dir1);
        let _ = fs::remove_dir_all(&dir2);

        assert_eq!(result.as_deref(), Some("text/markdown"));
    }

    #[test]
    fn globs_first_match_in_priority_order_wins() {
        // dir1 (higher priority) has text/plain for *.txt;
        // dir2 (lower priority) has text/x-log for *.txt.
        // dir1's entry should win.
        let dir1 = unique_dir("globs-priority-high");
        let dir2 = unique_dir("globs-priority-low");
        write_globs(&dir1, "text/plain:*.txt\n");
        write_globs(&dir2, "text/x-log:*.txt\n");

        let result =
            mime_from_data_dirs(Path::new("/var/log/app.txt"), &[dir1.clone(), dir2.clone()]);
        let _ = fs::remove_dir_all(&dir1);
        let _ = fs::remove_dir_all(&dir2);

        assert_eq!(result.as_deref(), Some("text/plain"));
    }

    #[test]
    fn returns_none_for_unknown_extension() {
        let dir = unique_dir("no-match");
        write_globs2(&dir, "50:text/plain:*.txt\n");

        let result = mime_from_data_dirs(
            Path::new("/tmp/file.xyzzy_elio_test"),
            std::slice::from_ref(&dir),
        );
        let _ = fs::remove_dir_all(&dir);

        assert!(result.is_none());
    }

    #[test]
    fn returns_none_when_data_dirs_empty() {
        let result = mime_from_data_dirs(Path::new("/tmp/file.txt"), &[]);
        assert!(result.is_none());
    }

    #[test]
    fn returns_none_for_path_with_no_extension() {
        let dir = unique_dir("no-ext");
        write_globs2(&dir, "50:text/plain:*.txt\n");

        let result = mime_from_data_dirs(Path::new("/usr/bin/ls"), std::slice::from_ref(&dir));
        let _ = fs::remove_dir_all(&dir);

        assert!(result.is_none());
    }

    // ── mime_from_xdg_database (system integration) ───────────────────────────
    // Uses the real XDG data dirs.  Skips gracefully if no MIME database is
    // present (e.g. minimal CI image).

    #[test]
    fn mime_from_xdg_database_returns_expected_type_for_common_extensions() {
        let has_db = super::super::xdg_data_dirs()
            .iter()
            .any(|d| d.join("mime/globs2").exists() || d.join("mime/globs").exists());
        if !has_db {
            return;
        }
        // .png is universally registered as image/png.
        let result = mime_from_xdg_database(Path::new("/any/path/image.png"));
        assert_eq!(
            result.as_deref(),
            Some("image/png"),
            "expected image/png for .png extension"
        );
    }
}