//! File picker widget for directory/file selection.
//!
//! Provides a file browser interface using the Tree widget.
//!
//! ## Example
//!
//! ```zig
//! var picker = try FilePicker.init(allocator, "/home/user");
//! defer picker.deinit();
//!
//! picker.render(area, buf);
//!
//! // Handle events
//! switch (event.key.code) {
//!     .up => picker.selectPrev(),
//!     .down => picker.selectNext(),
//!     .enter => {
//!         if (picker.getSelectedPath()) |path| {
//!             // Use selected file/directory
//!         }
//!     },
//! }
//! ```

const std = @import("std");
const fs = std.fs;
const Allocator = std.mem.Allocator;
const buffer_mod = @import("../buffer.zig");
const Buffer = buffer_mod.Buffer;
const Rect = buffer_mod.Rect;
const style_mod = @import("../style.zig");
const Style = style_mod.Style;
const Color = style_mod.Color;
const block_mod = @import("block.zig");
const Block = block_mod.Block;
const Borders = block_mod.Borders;

// ============================================================================
// FileEntry
// ============================================================================

/// Type of file entry.
pub const FileType = enum {
    file,
    directory,
    symlink,
    other,
};

/// A file or directory entry.
pub const FileEntry = struct {
    /// Entry name (not full path).
    name: []const u8,

    /// Full path.
    path: []const u8,

    /// Entry type.
    file_type: FileType,

    /// File size (for files).
    size: u64 = 0,

    /// Whether expanded (for directories).
    expanded: bool = false,

    /// Child entries (loaded lazily for directories).
    children: std.ArrayList(FileEntry),

    /// Whether children have been loaded.
    children_loaded: bool = false,

    /// Allocator for this entry.
    allocator: Allocator,

    /// Creates a new file entry.
    pub fn init(allocator: Allocator, name: []const u8, path: []const u8, file_type: FileType) !FileEntry {
        return .{
            .name = try allocator.dupe(u8, name),
            .path = try allocator.dupe(u8, path),
            .file_type = file_type,
            .children = std.ArrayList(FileEntry).init(allocator),
            .allocator = allocator,
        };
    }

    /// Frees all resources.
    pub fn deinit(self: *FileEntry) void {
        for (self.children.items) |*child| {
            child.deinit();
        }
        self.children.deinit();
        self.allocator.free(self.name);
        self.allocator.free(self.path);
    }

    /// Loads children from filesystem.
    pub fn loadChildren(self: *FileEntry) !void {
        if (self.children_loaded or self.file_type != .directory) return;

        var dir = fs.openDirAbsolute(self.path, .{ .iterate = true }) catch return;
        defer dir.close();

        var iter = dir.iterate();
        while (try iter.next()) |entry| {
            const entry_type: FileType = switch (entry.kind) {
                .file => .file,
                .directory => .directory,
                .sym_link => .symlink,
                else => .other,
            };

            // Build full path
            const full_path = try fs.path.join(self.allocator, &.{ self.path, entry.name });
            defer self.allocator.free(full_path);

            var child = try FileEntry.init(
                self.allocator,
                entry.name,
                full_path,
                entry_type,
            );

            // Get file size for files
            if (entry_type == .file) {
                if (dir.statFile(entry.name)) |stat| {
                    child.size = stat.size;
                } else |_| {}
            }

            try self.children.append(child);
        }

        // Sort: directories first, then alphabetically
        std.mem.sort(FileEntry, self.children.items, {}, struct {
            fn lessThan(_: void, a: FileEntry, b: FileEntry) bool {
                // Directories first
                if (a.file_type == .directory and b.file_type != .directory) return true;
                if (a.file_type != .directory and b.file_type == .directory) return false;
                // Then alphabetically (case-insensitive)
                return std.ascii.lessThanIgnoreCase(a.name, b.name);
            }
        }.lessThan);

        self.children_loaded = true;
    }

    /// Toggles expanded state.
    pub fn toggle(self: *FileEntry) !void {
        if (self.file_type == .directory) {
            self.expanded = !self.expanded;
            if (self.expanded and !self.children_loaded) {
                try self.loadChildren();
            }
        }
    }
};

// ============================================================================
// FilePicker
// ============================================================================

/// File picker icons.
pub const FileIcons = struct {
    directory: []const u8 = "📁 ",
    directory_open: []const u8 = "📂 ",
    file: []const u8 = "📄 ",
    symlink: []const u8 = "🔗 ",
    other: []const u8 = "❓ ",

    /// ASCII icons.
    pub const ascii = FileIcons{
        .directory = "[D] ",
        .directory_open = "[D] ",
        .file = "[F] ",
        .symlink = "[L] ",
        .other = "[?] ",
    };
};

/// File picker widget.
pub const FilePicker = struct {
    /// Allocator.
    allocator: Allocator,

    /// Root entry.
    root: FileEntry,

    /// Current path.
    current_path: []const u8,

    /// Selected item index (flattened).
    selected: usize = 0,

    /// Scroll offset.
    offset: usize = 0,

    /// Block wrapper.
    block: ?Block = null,

    /// Base style.
    style: Style = Style.default,

    /// Highlight style.
    highlight_style: Style = Style.default.bg(Color.blue).fg(Color.white),

    /// Directory style.
    dir_style: Style = Style.default.fg(Color.cyan).bold(),

    /// File icons.
    icons: FileIcons = .{},

    /// Show hidden files (starting with .).
    show_hidden: bool = false,

    /// Filter pattern (glob-like).
    filter: ?[]const u8 = null,

    /// Creates a file picker rooted at the given path.
    pub fn init(allocator: Allocator, root_path: []const u8) !FilePicker {
        // Normalize path
        const abs_path = try fs.realpathAlloc(allocator, root_path);

        var root = try FileEntry.init(allocator, fs.path.basename(abs_path), abs_path, .directory);
        root.expanded = true;
        try root.loadChildren();

        return .{
            .allocator = allocator,
            .root = root,
            .current_path = abs_path,
        };
    }

    /// Frees all resources.
    pub fn deinit(self: *FilePicker) void {
        self.root.deinit();
        self.allocator.free(self.current_path);
    }

    /// Sets the block wrapper.
    pub fn setBlock(self: *FilePicker, blk: Block) void {
        self.block = blk;
    }

    /// Sets whether to show hidden files.
    pub fn setShowHidden(self: *FilePicker, show: bool) void {
        self.show_hidden = show;
    }

    /// Sets file icons.
    pub fn setIcons(self: *FilePicker, icn: FileIcons) void {
        self.icons = icn;
    }

    /// Uses ASCII icons.
    pub fn useAsciiIcons(self: *FilePicker) void {
        self.icons = FileIcons.ascii;
    }

    /// Counts total visible entries.
    pub fn countVisible(self: *FilePicker) usize {
        return self.countVisibleEntry(&self.root);
    }

    fn countVisibleEntry(self: *FilePicker, entry: *FileEntry) usize {
        var count: usize = 1;
        if (entry.expanded) {
            for (entry.children.items) |*child| {
                if (!self.show_hidden and child.name.len > 0 and child.name[0] == '.') {
                    continue;
                }
                count += self.countVisibleEntry(child);
            }
        }
        return count;
    }

    /// Selects the next entry.
    pub fn selectNext(self: *FilePicker) void {
        const total = self.countVisible();
        if (self.selected < total - 1) {
            self.selected += 1;
        }
    }

    /// Selects the previous entry.
    pub fn selectPrev(self: *FilePicker) void {
        if (self.selected > 0) {
            self.selected -= 1;
        }
    }

    /// Toggles the selected entry (expand/collapse for directories).
    pub fn toggleSelected(self: *FilePicker) !void {
        var index: usize = 0;
        _ = try self.toggleAtIndex(&self.root, &index);
    }

    fn toggleAtIndex(self: *FilePicker, entry: *FileEntry, index: *usize) !bool {
        if (index.* == self.selected) {
            try entry.toggle();
            return true;
        }
        index.* += 1;

        if (entry.expanded) {
            for (entry.children.items) |*child| {
                if (!self.show_hidden and child.name.len > 0 and child.name[0] == '.') {
                    continue;
                }
                if (try self.toggleAtIndex(child, index)) {
                    return true;
                }
            }
        }
        return false;
    }

    /// Gets the selected entry.
    pub fn getSelectedEntry(self: *FilePicker) ?*FileEntry {
        var index: usize = 0;
        return self.getEntryAtIndex(&self.root, &index);
    }

    fn getEntryAtIndex(self: *FilePicker, entry: *FileEntry, index: *usize) ?*FileEntry {
        if (index.* == self.selected) {
            return entry;
        }
        index.* += 1;

        if (entry.expanded) {
            for (entry.children.items) |*child| {
                if (!self.show_hidden and child.name.len > 0 and child.name[0] == '.') {
                    continue;
                }
                if (self.getEntryAtIndex(child, index)) |found| {
                    return found;
                }
            }
        }
        return null;
    }

    /// Gets the path of the selected entry.
    pub fn getSelectedPath(self: *FilePicker) ?[]const u8 {
        if (self.getSelectedEntry()) |entry| {
            return entry.path;
        }
        return null;
    }

    /// Renders the file picker.
    pub fn render(self: *FilePicker, area: Rect, buf: *Buffer) void {
        // Clear area
        buf.setStyle(area, self.style);

        // Render block
        var picker_area = area;
        if (self.block) |blk| {
            blk.render(area, buf);
            picker_area = blk.inner(area);
        }

        if (picker_area.width < 4 or picker_area.height == 0) return;

        // Adjust scroll
        const visible = self.countVisible();
        if (self.selected >= self.offset + picker_area.height) {
            self.offset = self.selected - picker_area.height + 1;
        }
        if (self.selected < self.offset) {
            self.offset = self.selected;
        }

        // Render entries
        var y: u16 = picker_area.y;
        var index: usize = 0;
        self.renderEntry(picker_area, buf, &self.root, 0, &y, &index);

        _ = visible;
    }

    fn renderEntry(
        self: *FilePicker,
        area: Rect,
        buf: *Buffer,
        entry: *FileEntry,
        depth: u16,
        y: *u16,
        index: *usize,
    ) void {
        // Skip hidden files
        if (!self.show_hidden and depth > 0 and entry.name.len > 0 and entry.name[0] == '.') {
            return;
        }

        // Check if within visible range
        if (index.* >= self.offset and y.* < area.y + area.height) {
            var x = area.x;

            // Indentation
            const indent = depth * 2;
            x += indent;

            // Icon
            const icon = switch (entry.file_type) {
                .directory => if (entry.expanded) self.icons.directory_open else self.icons.directory,
                .file => self.icons.file,
                .symlink => self.icons.symlink,
                .other => self.icons.other,
            };
            _ = buf.setString(x, y.*, icon, self.style);
            x += @intCast(@min(icon.len, 4));

            // Style
            var entry_style = switch (entry.file_type) {
                .directory => self.dir_style,
                else => self.style,
            };

            // Highlight selected
            if (index.* == self.selected) {
                entry_style = self.highlight_style;
                // Fill line
                var hx = area.x;
                while (hx < area.x + area.width) : (hx += 1) {
                    if (buf.getCell(hx, y.*)) |cell| {
                        cell.setStyle(self.highlight_style);
                    }
                }
            }

            // Name
            const max_width = (area.x + area.width) -| x;
            const name_len: u16 = @intCast(@min(entry.name.len, max_width));
            if (name_len > 0) {
                _ = buf.setString(x, y.*, entry.name[0..name_len], entry_style);
            }

            y.* += 1;
        }

        index.* += 1;

        // Render children
        if (entry.expanded) {
            for (entry.children.items) |*child| {
                self.renderEntry(area, buf, child, depth + 1, y, index);
            }
        }
    }
};

// ============================================================================
// Tests
// ============================================================================

test "FileEntry basic" {
    const allocator = std.testing.allocator;
    var entry = try FileEntry.init(allocator, "test.txt", "/tmp/test.txt", .file);
    defer entry.deinit();

    try std.testing.expectEqualStrings("test.txt", entry.name);
    try std.testing.expectEqualStrings("/tmp/test.txt", entry.path);
    try std.testing.expectEqual(FileType.file, entry.file_type);
}

test "FilePicker init current dir" {
    const allocator = std.testing.allocator;

    // Try to init with current directory
    if (FilePicker.init(allocator, ".")) |*picker| {
        defer picker.deinit();

        try std.testing.expect(picker.countVisible() >= 1);
        try std.testing.expect(picker.getSelectedPath() != null);
    } else |_| {
        // Skip if directory cannot be opened
    }
}