worktrunk 0.35.0

//! Skim item implementations.
//!
//! Wrappers for ListItem and header row that implement SkimItem for the interactive selector.

use std::borrow::Cow;
use std::collections::HashSet;
use std::sync::Arc;

use anstyle::Reset;
use color_print::cformat;
use dashmap::DashMap;
use skim::prelude::*;
use worktrunk::git::Repository;
use worktrunk::styling::INFO_SYMBOL;

use super::super::list::model::ListItem;
use super::log_formatter::{
    FIELD_DELIM, batch_fetch_stats, format_log_output, process_log_with_dimming, strip_hash_markers,
};
use super::pager::{diff_pager, pipe_through_pager};
use super::preview::{PreviewMode, PreviewStateData};

/// Cache key for pre-computed previews: (branch_name, mode).
pub(super) type PreviewCacheKey = (String, PreviewMode);

/// Cache for pre-computed previews, keyed by (branch_name, mode).
/// Shared across all WorktreeSkimItems for background pre-computation.
pub(super) type PreviewCache = Arc<DashMap<PreviewCacheKey, String>>;

/// Header item for column names (non-selectable)
pub(super) struct HeaderSkimItem {
    pub display_text: String,
    pub display_text_with_ansi: String,
}

impl SkimItem for HeaderSkimItem {
    fn text(&self) -> Cow<'_, str> {
        Cow::Borrowed(&self.display_text)
    }

    fn display<'a>(&'a self, _context: skim::DisplayContext<'a>) -> skim::AnsiString<'a> {
        skim::AnsiString::parse(&self.display_text_with_ansi)
    }

    fn output(&self) -> Cow<'_, str> {
        Cow::Borrowed("") // Headers produce no output if selected
    }
}

/// Common diff rendering: check stat, show stat + full diff if non-empty.
fn compute_diff_preview(args: &[&str], no_changes_msg: &str, width: usize) -> String {
    let mut output = String::new();
    let Ok(repo) = Repository::current() else {
        return format!("{no_changes_msg}\n");
    };

    // Check stat output first
    let mut stat_args = args.to_vec();
    stat_args.push("--stat");
    stat_args.push("--color=always");
    let stat_width_arg = format!("--stat-width={}", width);
    stat_args.push(&stat_width_arg);

    if let Ok(stat) = repo.run_command(&stat_args)
        && !stat.trim().is_empty()
    {
        output.push_str(&stat);

        // Build diff args with color
        let mut diff_args = args.to_vec();
        diff_args.push("--color=always");

        if let Ok(diff) = repo.run_command(&diff_args) {
            output.push_str(&diff);
        }
    } else {
        output.push_str(no_changes_msg);
        output.push('\n');
    }

    output
}

/// Wrapper to implement SkimItem for ListItem
pub(super) struct WorktreeSkimItem {
    pub display_text: String,
    pub display_text_with_ansi: String,
    pub branch_name: String,
    pub item: Arc<ListItem>,
    /// Shared cache for pre-computed previews (all modes)
    pub preview_cache: PreviewCache,
}

impl SkimItem for WorktreeSkimItem {
    fn text(&self) -> Cow<'_, str> {
        Cow::Borrowed(&self.display_text)
    }

    fn display<'a>(&'a self, _context: skim::DisplayContext<'a>) -> skim::AnsiString<'a> {
        skim::AnsiString::parse(&self.display_text_with_ansi)
    }

    fn output(&self) -> Cow<'_, str> {
        Cow::Borrowed(&self.branch_name)
    }

    fn preview(&self, context: PreviewContext<'_>) -> ItemPreview {
        let mode = PreviewStateData::read_mode();

        // Build preview: tabs header + content
        let mut result = Self::render_preview_tabs(mode);
        result.push_str(&self.preview_for_mode(mode, context.width, context.height));

        ItemPreview::AnsiText(result)
    }
}

impl WorktreeSkimItem {
    /// Render the tab header for the preview window
    ///
    /// Shows all preview modes as tabs, with the current mode bolded
    /// and unselected modes dimmed. Controls shown below in normal text
    /// for visual distinction from inactive tabs.
    pub(super) fn render_preview_tabs(mode: PreviewMode) -> String {
        // Full SGR reset (\x1b[0m) to ensure clean state between styled elements.
        // Using anstyle::Reset instead of cformat's </> (\x1b[22m) because some terminals
        // don't properly handle the intensity-only reset after bold text. This matches
        // the pattern used in src/styling/format.rs for similar ANSI reset handling.
        let reset = Reset;

        /// Format a tab label with bold (active) or dimmed (inactive) styling
        fn format_tab(label: &str, is_active: bool) -> String {
            if is_active {
                cformat!("<bold>{}</>", label)
            } else {
                cformat!("<dim>{}</>", label)
            }
        }

        let tab1 = format_tab("1: HEAD±", mode == PreviewMode::WorkingTree);
        let tab2 = format_tab("2: log", mode == PreviewMode::Log);
        let tab3 = format_tab("3: main…±", mode == PreviewMode::BranchDiff);
        let tab4 = format_tab("4: remote⇅", mode == PreviewMode::UpstreamDiff);
        let tab5 = format_tab("5: summary", mode == PreviewMode::Summary);

        // Controls use dim yellow to distinguish from dimmed (white) tabs
        let controls = cformat!(
            "<dim,yellow>Enter: switch | alt-c: create | Esc: cancel | ctrl-u/d: scroll | alt-p: toggle</>"
        );

        // End each tab and controls with full reset to prevent style bleeding
        // into dividers and preview content
        format!(
            "{tab1}{reset} | {tab2}{reset} | {tab3}{reset} | {tab4}{reset} | {tab5}{reset}\n{controls}{reset}\n\n"
        )
    }

    /// Render preview for the given mode with specified dimensions.
    /// Uses cache if available, otherwise computes and caches.
    /// Post-processing (diff pager, markdown render) applied at display time.
    fn preview_for_mode(&self, mode: PreviewMode, width: usize, height: usize) -> String {
        let cache_key = (self.branch_name.clone(), mode);

        let content = self
            .preview_cache
            .entry(cache_key)
            .or_insert_with(|| Self::compute_preview(&self.item, mode, width, height))
            .value()
            .clone();

        // Post-processing at display time (not cached)
        match mode {
            PreviewMode::Summary => super::summary::render_summary(&content, width),
            PreviewMode::WorkingTree | PreviewMode::BranchDiff | PreviewMode::UpstreamDiff => {
                if let Some(pager_cmd) = diff_pager() {
                    pipe_through_pager(&content, pager_cmd, width)
                } else {
                    content
                }
            }
            PreviewMode::Log => content,
        }
    }

    /// Compute preview for any mode. Called from cache miss and background pre-computation.
    pub(super) fn compute_preview(
        item: &ListItem,
        mode: PreviewMode,
        width: usize,
        height: usize,
    ) -> String {
        match mode {
            PreviewMode::WorkingTree => Self::compute_working_tree_preview(item, width),
            PreviewMode::Log => Self::compute_log_preview(item, width, height),
            PreviewMode::BranchDiff => Self::compute_branch_diff_preview(item, width),
            PreviewMode::UpstreamDiff => Self::compute_upstream_diff_preview(item, width),
            PreviewMode::Summary => Self::compute_summary_preview(item),
        }
    }

    /// Compute Tab 1: Working tree preview (uncommitted changes vs HEAD)
    fn compute_working_tree_preview(item: &ListItem, width: usize) -> String {
        let Some(wt_info) = item.worktree_data() else {
            let branch = item.branch_name();
            return format!(
                "{INFO_SYMBOL} {branch} is branch only — press Enter to create worktree\n"
            );
        };

        let branch = item.branch_name();
        let path = wt_info.path.display().to_string();

        compute_diff_preview(
            &["-C", &path, "diff", "HEAD"],
            &cformat!("{INFO_SYMBOL} <bold>{branch}</> has no uncommitted changes"),
            width,
        )
    }

    /// Compute Tab 3: Branch diff preview (line diffs in commits ahead of default branch)
    fn compute_branch_diff_preview(item: &ListItem, width: usize) -> String {
        let branch = item.branch_name();
        let Ok(repo) = Repository::current() else {
            return cformat!("{INFO_SYMBOL} <bold>{branch}</> has no commits ahead of main\n");
        };
        let Some(default_branch) = repo.default_branch() else {
            return cformat!("{INFO_SYMBOL} <bold>{branch}</> has no commits ahead of main\n");
        };
        if item.counts.is_some_and(|c| c.ahead == 0) {
            return cformat!(
                "{INFO_SYMBOL} <bold>{branch}</> has no commits ahead of <bold>{default_branch}</>\n"
            );
        }

        let merge_base = format!("{}...{}", default_branch, item.head());
        compute_diff_preview(
            &["diff", &merge_base],
            &cformat!(
                "{INFO_SYMBOL} <bold>{branch}</> has no file changes vs <bold>{default_branch}</>"
            ),
            width,
        )
    }

    /// Compute Tab 4: Upstream diff preview (ahead/behind vs tracking branch)
    fn compute_upstream_diff_preview(item: &ListItem, width: usize) -> String {
        let branch = item.branch_name();

        let Some(active) = item.upstream.as_ref().and_then(|u| u.active()) else {
            return cformat!("{INFO_SYMBOL} <bold>{branch}</> has no upstream tracking branch\n");
        };

        let upstream_ref = format!("{}@{{u}}", branch);

        if active.ahead == 0 && active.behind == 0 {
            return cformat!("{INFO_SYMBOL} <bold>{branch}</> is up to date with upstream\n");
        }

        if active.ahead > 0 && active.behind > 0 {
            let range = format!("{}...{}", upstream_ref, item.head());
            compute_diff_preview(
                &["diff", &range],
                &cformat!(
                    "{INFO_SYMBOL} <bold>{branch}</> has diverged (⇡{} ⇣{}) but no unique file changes",
                    active.ahead,
                    active.behind
                ),
                width,
            )
        } else if active.ahead > 0 {
            let range = format!("{}...{}", upstream_ref, item.head());
            compute_diff_preview(
                &["diff", &range],
                &cformat!("{INFO_SYMBOL} <bold>{branch}</> has no unpushed file changes"),
                width,
            )
        } else {
            let range = format!("{}...{}", item.head(), upstream_ref);
            compute_diff_preview(
                &["diff", &range],
                &cformat!(
                    "{INFO_SYMBOL} <bold>{branch}</> is behind upstream (⇣{}) but no file changes",
                    active.behind
                ),
                width,
            )
        }
    }

    /// Compute log preview for a worktree item.
    /// This can be called from background threads for pre-computation.
    pub(super) fn compute_log_preview(item: &ListItem, width: usize, height: usize) -> String {
        // Minimum preview width to show timestamps (adds ~7 chars: space + 4-char time + space)
        // Note: preview is typically 50% of terminal width, so 50 = 100-col terminal
        const TIMESTAMP_WIDTH_THRESHOLD: usize = 50;
        // Tab header takes 3 lines (tabs + controls + blank)
        const HEADER_LINES: usize = 3;

        let mut output = String::new();
        let show_timestamps = width >= TIMESTAMP_WIDTH_THRESHOLD;
        // Calculate how many log lines fit in preview (height minus header)
        let log_limit = height.saturating_sub(HEADER_LINES).max(1);
        let head = item.head();
        let branch = item.branch_name();
        let Ok(repo) = Repository::current() else {
            output.push_str(&cformat!(
                "{INFO_SYMBOL} <bold>{branch}</> has no commits\n"
            ));
            return output;
        };
        let Some(default_branch) = repo.default_branch() else {
            output.push_str(&cformat!(
                "{INFO_SYMBOL} <bold>{branch}</> has no commits\n"
            ));
            return output;
        };

        // Get merge-base with default branch
        //
        // Note on error handling: This code runs in an interactive preview pane that updates
        // on every keystroke. We intentionally use silent fallbacks rather than propagating
        // errors to avoid disruptive error messages during navigation. The preview is
        // supplementary - users can still select worktrees even if preview fails.
        //
        // Alternative: Check specific conditions (default branch exists, valid HEAD, etc.) before
        // running git commands. This would provide better diagnostics but adds latency to
        // every preview render. Trade-off: simplicity + speed vs. detailed error messages.
        let Ok(merge_base_output) = repo.run_command(&["merge-base", &default_branch, head]) else {
            output.push_str(&cformat!(
                "{INFO_SYMBOL} <bold>{branch}</> has no commits\n"
            ));
            return output;
        };

        let merge_base = merge_base_output.trim();
        let is_default_branch = branch == default_branch;

        // Format strings for git log
        // Without timestamps: hash (colored/dimmed), then message
        // Format includes full hash (for matching) between SOH and NUL delimiters.
        // Display content uses \x1f to separate fields for timestamp parsing.
        // Format: SOH full_hash NUL short_hash \x1f timestamp \x1f decorations+message
        // Using delimiters allows parsing without assuming fixed hash length (SHA-256 safe)
        // Note: Use %x01/%x00 (git's hex escapes) to avoid embedding control chars in argv
        let timestamp_format = format!(
            "--format=%x01%H%x00%C(auto)%h{}%ct{}%C(auto)%d%C(reset) %s",
            FIELD_DELIM, FIELD_DELIM
        );
        let no_timestamp_format = "--format=%x01%H%x00%C(auto)%h%C(auto)%d%C(reset) %s";

        let log_limit_str = log_limit.to_string();

        // Get commits after merge-base (for dimming logic)
        // These are commits reachable from HEAD but not from merge-base, shown bright.
        // Commits before merge-base (shared with default branch) are shown dimmed.
        // Bounded to log_limit since we only need to check displayed commits.
        let unique_commits: Option<HashSet<String>> = if is_default_branch {
            // On default branch: no dimming (None means show everything bright)
            None
        } else {
            // On feature branch: get commits unique to this branch
            // rev-list A...B --right-only gives commits reachable from B but not A
            let range = format!("{}...{}", merge_base, head);
            let commits = repo
                .run_command(&["rev-list", &range, "--right-only", "-n", &log_limit_str])
                .map(|out| out.lines().map(String::from).collect())
                .unwrap_or_default();
            Some(commits) // Some(empty) means dim everything
        };

        // Get graph output (no --numstat to avoid blank continuation lines)
        let format: &str = if show_timestamps {
            &timestamp_format
        } else {
            no_timestamp_format
        };
        let args = vec![
            "log",
            "--graph",
            "--no-show-signature",
            format,
            "--color=always",
            "-n",
            &log_limit_str,
            head,
        ];

        if let Ok(log_output) = repo.run_command(&args) {
            let (processed, hashes) =
                process_log_with_dimming(&log_output, unique_commits.as_ref());
            if show_timestamps {
                // Batch fetch stats for all commits
                let stats = batch_fetch_stats(&repo, &hashes);
                output.push_str(&format_log_output(&processed, &stats));
            } else {
                // Strip hash markers (SOH...NUL) since we're not using format_log_output
                output.push_str(&strip_hash_markers(&processed));
            }
        }

        output
    }

    /// Compute Tab 5: Summary preview (LLM-generated branch summary)
    ///
    /// Returns a synchronous placeholder when the background summary generation
    /// hasn't completed yet. The actual summary is generated by background threads
    /// and inserted into the preview cache.
    fn compute_summary_preview(_item: &ListItem) -> String {
        format!(
            "{INFO_SYMBOL} Generating summary...\n\n\
             Press 5 again to refresh once generation completes.\n"
        )
    }
}

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

    #[test]
    fn test_render_preview_tabs() {
        // All PreviewMode variants: verify tab labels, active styling, and structure
        for (name, mode) in [
            ("working_tree", PreviewMode::WorkingTree),
            ("log", PreviewMode::Log),
            ("branch_diff", PreviewMode::BranchDiff),
            ("upstream_diff", PreviewMode::UpstreamDiff),
            ("summary", PreviewMode::Summary),
        ] {
            assert_snapshot!(name, WorktreeSkimItem::render_preview_tabs(mode));
        }
    }

    #[test]
    fn test_compute_summary_preview() {
        // All inputs produce the same synchronous placeholder.
        // The background thread produces the real summary (or "No changes to summarize"
        // for the default branch).
        use crate::commands::list::model::{ItemKind, WorktreeData};

        let mut main_item = ListItem::new_branch("abc123".to_string(), "main".to_string());
        main_item.kind = ItemKind::Worktree(Box::new(WorktreeData {
            is_main: true,
            ..Default::default()
        }));

        let feature_item = ListItem::new_branch("abc123".to_string(), "feature".to_string());

        // Direct call and compute_preview dispatch both return the placeholder
        assert_snapshot!(
            "direct",
            WorktreeSkimItem::compute_summary_preview(&main_item)
        );
        assert_snapshot!(
            "via_compute_preview",
            WorktreeSkimItem::compute_preview(&feature_item, PreviewMode::Summary, 80, 40)
        );
    }

    #[test]
    fn test_preview_for_mode_summary_cache() {
        // Cache hit returns cached content; cache miss computes the placeholder
        let item = Arc::new(ListItem::new_branch(
            "abc123".to_string(),
            "feature".to_string(),
        ));

        let cache_hit = {
            let preview_cache: PreviewCache = Arc::new(DashMap::new());
            preview_cache.insert(
                ("feature".to_string(), PreviewMode::Summary),
                "Add auth module\n\nImplements JWT-based authentication.".to_string(),
            );
            WorktreeSkimItem {
                display_text: String::new(),
                display_text_with_ansi: String::new(),
                branch_name: "feature".to_string(),
                item: Arc::clone(&item),
                preview_cache,
            }
        };

        let cache_miss = {
            let preview_cache: PreviewCache = Arc::new(DashMap::new());
            WorktreeSkimItem {
                display_text: String::new(),
                display_text_with_ansi: String::new(),
                branch_name: "feature".to_string(),
                item: Arc::clone(&item),
                preview_cache,
            }
        };

        assert_snapshot!(
            "cache_hit",
            cache_hit.preview_for_mode(PreviewMode::Summary, 80, 40)
        );
        assert_snapshot!(
            "cache_miss",
            cache_miss.preview_for_mode(PreviewMode::Summary, 80, 40)
        );
    }

    #[test]
    fn test_render_preview_tabs_ansi_codes() {
        // Test that ANSI escape sequences properly reset to prevent style bleeding
        let output = WorktreeSkimItem::render_preview_tabs(PreviewMode::WorkingTree);

        let first_line = output.lines().next().unwrap();
        let second_line = output.lines().nth(1).unwrap();

        // Each styled tab should end with a full reset (\x1b[0m) before the divider
        // This prevents bold/dim from bleeding into the " | " dividers
        let full_reset = "\x1b[0m";

        // Count resets - should have one after each of the 5 tabs
        assert_eq!(first_line.matches(full_reset).count(), 5);

        // The sequence should be: style + text + [22m + [0m + divider
        // Check that dividers come after full resets
        let parts: Vec<&str> = first_line.split(" | ").collect();
        assert_eq!(parts.len(), 5);
        assert!(parts.iter().all(|part| part.ends_with(full_reset)));

        // Controls line should end with full reset to ensure clean state for preview content
        assert!(second_line.ends_with(full_reset));
    }
}