//! Directory panes, acme's directory windows (plan9port acme text.c,
//! textload and textcolumnate): a look at a directory opens a pane named
//! for it with a trailing `/`, its body the directory's entries in columns
//! that fit the pane, a directory's marked with a `/`. A look at an entry
//! is a look from that directory; Get, or a look at the directory again,
//! reads it again. Otherwise it is a text pane like +Errors (Output's
//! `.dir`): searched, selected and edited as any, and never dirty.
const std = @import("std");
const pardes = @import("pardes.zig");
const panes = @import("panes.zig");
const config = @import("config.zig");
const exec = @import("exec.zig");
const filesystem = @import("fs.zig");
const limits = @import("memory.zig").limits;
const Pardes = pardes.Pardes;
const Pane = panes.Pane;
const File = panes.File;

/// What a directory pane keeps of its listing, as acme's Window keeps
/// dlp/ndl: the entries, for a change of width to lay them out again.
pub const State = struct {
    /// The entries, sorted, each ending in a newline; gpa-owned.
    names: []u8,
    /// The text width they were laid out at (none yet: the most there is),
    /// and the text's revision then: a body edited since is left as it is.
    width: usize = std.math.maxInt(usize),
    revision: u32 = 0,
};

/// acme's tab in a directory window (text.c TABDIR), in cells: a column is
/// a whole number of them, at least a cell wider than its widest entry.
const tab = 3;

/// The directory a pane named `name` works in, as acme's dirname reads a
/// window's name: a directory pane's (ending in `/`) is its own, a file's
/// the one it is in.
pub fn ofName(name: []const u8) []const u8 {
    if (std.mem.endsWith(u8, name, "/")) {
        const dir = std.mem.trimEnd(u8, name, "/");
        return if (dir.len == 0) "/" else dir;
    }
    return std.fs.path.dirname(name) orelse "/";
}

/// The entries of directory `dir` on this host as acme lists them
/// (plan9port lib9 dirread, acme's dircmp): every name but `.` and `..`,
/// dotfiles too; a directory's, a link to one's too, ending in `/`; sorted
/// bytewise, the `/` counted; each ending in a newline.
pub fn read(gpa: std.mem.Allocator, dir: []const u8) ![]u8 {
    if (comptime !filesystem.platform_has_fs) return error.FileNotFound;
    const local = filesystem.localPath(dir) orelse return error.NotLocal;
    // Its own copy: the caller's may be a pane's, gone while the turn is out.
    var own: [4096]u8 = undefined;
    if (local.len > own.len) return error.NameTooLong;
    @memcpy(own[0..local.len], local);
    var entries: std.ArrayList([]u8) = .empty;
    defer {
        for (entries.items) |entry| gpa.free(entry);
        entries.deinit(gpa);
    }
    var total: usize = 0;
    {
        pardes.turn.yield();
        defer pardes.turn.back();
        const io = std.Io.Threaded.global_single_threaded.io();
        var d = try std.Io.Dir.cwd().openDir(io, own[0..local.len], .{ .iterate = true });
        defer d.close(io);
        var it = d.iterate();
        while (try it.next(io)) |entry| {
            if (std.mem.eql(u8, entry.name, ".") or std.mem.eql(u8, entry.name, "..")) continue;
            const is_dir = switch (entry.kind) {
                .directory => true,
                // Followed, as dirread's stat is: a link to a directory is one.
                .sym_link, .unknown => if (d.statFile(io, entry.name, .{})) |st| st.kind == .directory else |_| false,
                else => false,
            };
            total += entry.name.len + 2;
            if (total > limits.max_file_bytes) return error.FileTooLarge;
            const name = try std.mem.concat(gpa, u8, &.{ entry.name, if (is_dir) "/" else "" });
            entries.append(gpa, name) catch |err| {
                gpa.free(name);
                return err;
            };
        }
    }
    std.mem.sort([]u8, entries.items, {}, struct {
        fn lt(_: void, a: []u8, b: []u8) bool {
            return std.mem.lessThan(u8, a, b);
        }
    }.lt);
    var out: std.ArrayList(u8) = .empty;
    errdefer out.deinit(gpa);
    try out.ensureTotalCapacity(gpa, total);
    for (entries.items) |entry| {
        out.appendSliceAssumeCapacity(entry);
        out.appendAssumeCapacity('\n');
    }
    return out.toOwnedSlice(gpa);
}

/// `entries` in columns at most `width` cells wide, as acme's
/// textcolumnate lays them out with its 3-cell tabs: down each column
/// first, every column as wide as the widest entry and a cell more,
/// rounded up to a tab, and each row ending in a newline. Blanks pad where
/// acme's tabs do: a pardes tab is a fixed width, not a stop.
pub fn columnate(gpa: std.mem.Allocator, entries: []const []const u8, width: usize) ![]u8 {
    var colw: usize = 0;
    for (entries) |entry| {
        const w = File.displayWidth(entry) + 1;
        colw = @max(colw, (w + tab - 1) / tab * tab);
    }
    const ncol = if (colw == 0) 1 else @max(1, width / colw);
    const nrow = (entries.len + ncol - 1) / ncol;
    var out: std.ArrayList(u8) = .empty;
    errdefer out.deinit(gpa);
    for (0..nrow) |row| {
        var j = row;
        while (j < entries.len) : (j += nrow) {
            try out.appendSlice(gpa, entries[j]);
            if (j + nrow >= entries.len) break;
            try out.appendNTimes(gpa, ' ', colw - File.displayWidth(entries[j]));
        }
        try out.append(gpa, '\n');
    }
    return out.toOwnedSlice(gpa);
}

/// The cells a directory pane `cols` wide lays its entries out in: what
/// is left of a row after the line numbers and the cell a wrap keeps
/// (File.wrapWidth), the numbers as wide as `count` lines would need.
fn textWidth(cols: usize, count: usize) usize {
    var lines = count + 1;
    var digits: usize = 1;
    while (lines >= 10) : (lines /= 10) digits += 1;
    return cols -| @max(config.PREFIX_W, digits + 1) -| 1;
}

/// Lays the pane's entries out again `cols` wide, when the width they need
/// changed and the body is still theirs: a body edited since is kept, as
/// typed, until a Get or a look at the directory reads it again.
pub fn fit(p: *Pardes, pane: *Pane, cols: usize) void {
    const f = if (pane.file) |*file| file else return;
    const l = if (f.listing) |*listing| listing else return;
    const count = std.mem.count(u8, l.names, "\n");
    const width = textWidth(cols, count);
    if (f.revision != l.revision or width == l.width) return;
    // Not the scratch arena: this runs from sync, on every event.
    const entries = p.gpa.alloc([]const u8, count) catch return;
    defer p.gpa.free(entries);
    var it = std.mem.splitScalar(u8, l.names, '\n');
    for (entries) |*entry| entry.* = it.next().?;
    const text = columnate(p.gpa, entries, width) catch return;
    if (std.mem.eql(u8, text, f.content)) p.gpa.free(text) else {
        File.setContent(p, f, text);
        panes.Output.resetBody(p, pane);
    }
    l.width = width;
    l.revision = f.revision;
}

/// Reads pane `id`'s directory again and lays it out anew, its edits gone,
/// as acme's Get does in a directory window.
pub fn refresh(p: *Pardes, id: usize) !void {
    const pane = p.panes[id] orelse return error.NoPane;
    const serial = pane.serial;
    const names = try read(p.gpa, ofName(pane.file.?.path));
    // The pane may have closed while the turn was out.
    const now = p.panes[id] orelse return p.gpa.free(names);
    if (now.serial != serial) return p.gpa.free(names);
    const f = &now.file.?;
    const l = &f.listing.?;
    p.gpa.free(l.names);
    l.names = names;
    l.width = std.math.maxInt(usize);
    l.revision = f.revision;
    fit(p, now, now.cols);
    panes.Output.resetBody(p, now);
}

/// A look at directory `dir` (look.zig's `.dir`, with `DirLook pane`): its
/// pane, read again, or a new one, placed as a document is.
pub fn look(p: *Pardes, from: usize, dir: []const u8) void {
    const name = (if (std.mem.endsWith(u8, dir, "/"))
        p.gpa.dupe(u8, dir)
    else
        std.mem.concat(p.gpa, u8, &.{ dir, "/" })) catch |err| return p.reportError(from, "look", err);
    for (p.panes, 0..) |slot, i| {
        const pane = slot orelse continue;
        const f = pane.file orelse continue;
        if (f.listing == null or !std.mem.eql(u8, f.path, name)) continue;
        p.gpa.free(name);
        return show(p, from, i);
    }
    var said: [limits.host_path_cap + 16]u8 = undefined;
    const what = std.fmt.bufPrint(&said, "look: {s}", .{name[0..@min(name.len, limits.host_path_cap)]}) catch "look";
    const names = read(p.gpa, dir) catch |err| {
        p.gpa.free(name);
        return p.reportError(from, what, err);
    };
    const free = p.freeSlot() orelse {
        p.gpa.free(name);
        p.gpa.free(names);
        return p.reportError(from, "look", error.NoPaneSlots);
    };
    const pane = open(p, free, name, names) catch |err| return p.reportError(from, "look", err);
    const failures = p.fs.failures;
    exec.placeNew(p, from, from, free, .doc);
    // Refused a place: that is the look's one failure.
    if (p.fs.failures != failures) return;
    fit(p, pane, @max(1, p.rects[free].w -| config.GUTTER));
}

/// A pane on directory `name` (ending in `/`) with its entries `names`,
/// both taken, in slot `id`, not yet placed and laid out.
pub fn open(p: *Pardes, id: usize, name: []u8, names: []u8) !*Pane {
    errdefer p.gpa.free(name);
    errdefer p.gpa.free(names);
    const content = try p.gpa.dupe(u8, "");
    errdefer p.gpa.free(content);
    const history = try File.History.create(p.gpa);
    errdefer p.gpa.destroy(history);
    const pane = try p.newDocPane(id);
    pane.file = .{
        .path = name,
        .content = content,
        .output = .{ .from = .dir },
        .history = history,
        .listing = .{ .names = names },
    };
    pane.body.cur_pinned = true;
    return pane;
}

/// The directory pane `id` read again and given the keyboard, a look at it
/// coming from pane `from`.
pub fn show(p: *Pardes, from: usize, id: usize) void {
    const pane = p.panes[id] orelse return;
    const serial = pane.serial;
    var said: [limits.host_path_cap + 16]u8 = undefined;
    const name = pane.file.?.path;
    const what = std.fmt.bufPrint(&said, "look: {s}", .{name[0..@min(name.len, limits.host_path_cap)]}) catch "look";
    refresh(p, id) catch |err| return p.reportError(from, what, err);
    // Closed while the turn was out: nothing to give the keyboard to.
    const now = p.panes[id] orelse return;
    if (now.serial == serial) p.active = id;
}

// ---- tests ----

const testing = std.testing;

fn laidOut(names: []const []const u8, width: usize) ![]u8 {
    return columnate(testing.allocator, names, width);
}

test "entries go down each column first, a column a tab wider than its widest entry, as acme's" {
    // The widest, 5 cells, makes 6: two tabs. 20 cells take three columns.
    const names = [_][]const u8{ "a", "bb", "ccc/", "ddddd", "e", "f", "g" };
    const text = try laidOut(&names, 20);
    defer testing.allocator.free(text);
    try testing.expectEqualStrings(
        "a     ddddd g\n" ++
            "bb    e\n" ++
            "ccc/  f\n",
        text,
    );
}

test "a width that is a whole number of tabs takes one more cell, so a column never touches the next" {
    // "abc" is 3 cells, a tab exactly: its column is 6, not 3.
    const names = [_][]const u8{ "abc", "de", "f" };
    const text = try laidOut(&names, 12);
    defer testing.allocator.free(text);
    try testing.expectEqualStrings("abc   f\nde\n", text);
}

test "one column when a row has room for no more, and nothing at all for an empty directory" {
    const names = [_][]const u8{ "alpha", "beta" };
    const narrow = try laidOut(&names, 4);
    defer testing.allocator.free(narrow);
    try testing.expectEqualStrings("alpha\nbeta\n", narrow);
    const none = try laidOut(&.{}, 80);
    defer testing.allocator.free(none);
    try testing.expectEqualStrings("", none);
}

test "a wide character counts its cells, not its bytes" {
    // 世界 is 4 cells: its column is 6 cells, padded with two blanks.
    const names = [_][]const u8{ "世界", "x" };
    const text = try laidOut(&names, 12);
    defer testing.allocator.free(text);
    try testing.expectEqualStrings("世界  x\n", text);
}

test "a directory reads as acme lists it: dotfiles kept, . and .. not, directories and links to them marked, sorted bytewise" {
    if (comptime !filesystem.platform_has_fs) return;
    var tmp = testing.tmpDir(.{});
    defer tmp.cleanup();
    const io = testing.io;
    try tmp.dir.writeFile(io, .{ .sub_path = "b.txt", .data = "" });
    try tmp.dir.writeFile(io, .{ .sub_path = ".hidden", .data = "" });
    try tmp.dir.writeFile(io, .{ .sub_path = "B", .data = "" });
    try tmp.dir.createDir(io, "a", .default_dir);
    try tmp.dir.createDir(io, "a.d", .default_dir);
    try tmp.dir.symLink(io, "a", "link", .{ .is_directory = true });
    var buf: [4096]u8 = undefined;
    const dir = buf[0..try tmp.dir.realPath(io, &buf)];
    const names = try read(testing.allocator, dir);
    defer testing.allocator.free(names);
    // Bytewise, as dircmp's memcmp: `.` before capitals before small
    // letters, and `a.d/` before `a/` because `.` is before `/`.
    try testing.expectEqualStrings(".hidden\nB\na.d/\na/\nb.txt\nlink/\n", names);
}

test "a directory pane's directory is its own name, a file's the one it is in" {
    try testing.expectEqualStrings("/a/b", ofName("/a/b/"));
    try testing.expectEqualStrings("/", ofName("/"));
    try testing.expectEqualStrings("/a", ofName("/a/b"));
    try testing.expectEqualStrings("/", ofName("/a"));
}

/// A session on a file in a fresh directory holding `sub/inner.txt`,
/// `top.txt` and `.dot`: the directory's path in `buf`.
fn session(tmp: *std.testing.TmpDir, buf: *[4096]u8) !struct { p: *Pardes, dir: []const u8 } {
    const io = testing.io;
    try tmp.dir.createDir(io, "sub", .default_dir);
    try tmp.dir.writeFile(io, .{ .sub_path = "sub/inner.txt", .data = "inner\n" });
    try tmp.dir.writeFile(io, .{ .sub_path = "top.txt", .data = "top\n" });
    try tmp.dir.writeFile(io, .{ .sub_path = ".dot", .data = "" });
    const dir = buf[0..try tmp.dir.realPath(io, buf)];
    var path_buf: [4200]u8 = undefined;
    const path = try std.fmt.bufPrint(&path_buf, "{s}/top.txt", .{dir});
    const p = try Pardes.init(testing.allocator, .{ .file = path, .tty_only = true, .cols = 80, .rows = 30 });
    while (p.nextEffect()) |_| {}
    return .{ .p = p, .dir = dir };
}

/// The pane named `name`, and how many are.
fn named(p: *Pardes, name: []const u8) struct { id: ?usize, count: usize } {
    var id: ?usize = null;
    var count: usize = 0;
    for (p.panes, 0..) |slot, i| if (slot) |pane| if (pane.file) |f| if (std.mem.eql(u8, f.path, name)) {
        id = i;
        count += 1;
    };
    return .{ .id = id, .count = count };
}

test "a look at a directory opens a pane named for it with a /, its entries in columns, never dirty, its directory its own" {
    if (comptime !pardes.hosted) return;
    var tmp = testing.tmpDir(.{});
    defer tmp.cleanup();
    var buf: [4096]u8 = undefined;
    const s = try session(&tmp, &buf);
    defer s.p.deinit();
    const p = s.p;
    pardes.look.lookAt(p, 0, s.dir);
    p.sync();
    var name_buf: [4200]u8 = undefined;
    const name = try std.fmt.bufPrint(&name_buf, "{s}/", .{s.dir});
    const id = named(p, name).id orelse return error.NoDirectoryPane;
    try testing.expectEqual(id, p.active);
    const pane = p.panes[id].?;
    try testing.expectEqualStrings(".dot     sub/     top.txt\n", pane.file.?.content);
    try testing.expectEqualStrings(@import("tagline.zig").dir_pane_tail, @import("tagline.zig").curTail(pane));
    try testing.expectEqualStrings(s.dir, Pardes.paneDir(pane));
    // Edited, still never dirty, and no Save writes it.
    try testing.expect(p.executeBuiltinLine(id, "Edit ,d"));
    try testing.expectEqualStrings("", pane.file.?.content);
    try testing.expect(!@import("tagline.zig").dirty(pane));
    const failures = p.fs.failures;
    try testing.expect(p.executeBuiltinLine(id, "Save"));
    try testing.expect(p.executeBuiltinLine(id, "Save elsewhere.txt"));
    try testing.expectEqual(failures +% 2, p.fs.failures);
    try testing.expect(p.panes[id].?.prompt == .none);
}

test "a look at an entry is a look from the directory, .. goes up to the open pane, and Get or a look again reads it again" {
    if (comptime !pardes.hosted) return;
    var tmp = testing.tmpDir(.{});
    defer tmp.cleanup();
    var buf: [4096]u8 = undefined;
    const s = try session(&tmp, &buf);
    defer s.p.deinit();
    const p = s.p;
    var name_buf: [4200]u8 = undefined;
    pardes.look.lookAt(p, 0, s.dir);
    p.sync();
    const top = named(p, try std.fmt.bufPrint(&name_buf, "{s}/", .{s.dir})).id.?;
    // An entry that is a directory: a pane of its own.
    pardes.look.lookAt(p, top, "sub/");
    p.sync();
    const sub = named(p, try std.fmt.bufPrint(&name_buf, "{s}/sub/", .{s.dir})).id orelse return error.NoSubPane;
    try testing.expectEqualStrings("inner.txt\n", p.panes[sub].?.file.?.content);
    // A file in it, by its name alone: that directory's file.
    pardes.look.lookAt(p, sub, "inner.txt");
    p.sync();
    try testing.expect(named(p, try std.fmt.bufPrint(&name_buf, "{s}/sub/inner.txt", .{s.dir})).id != null);
    // `..`: the open pane above, read again, not a second one.
    try tmp.dir.writeFile(testing.io, .{ .sub_path = "new.txt", .data = "" });
    pardes.look.lookAt(p, sub, "..");
    p.sync();
    const again = named(p, try std.fmt.bufPrint(&name_buf, "{s}/", .{s.dir}));
    try testing.expectEqual(@as(usize, 1), again.count);
    try testing.expectEqual(top, p.active);
    try testing.expect(std.mem.indexOf(u8, p.panes[top].?.file.?.content, "new.txt") != null);
    // Get, in its tag or its text: read again.
    try tmp.dir.writeFile(testing.io, .{ .sub_path = "sub/later.txt", .data = "" });
    try testing.expect(p.executeBuiltinLine(sub, "Get"));
    try testing.expectEqualStrings("inner.txt   later.txt\n", p.panes[sub].?.file.?.content);
}

test "an exec in a directory pane runs in its directory, and its +Errors goes there" {
    if (comptime !pardes.hosted) return;
    var tmp = testing.tmpDir(.{});
    defer tmp.cleanup();
    var buf: [4096]u8 = undefined;
    const s = try session(&tmp, &buf);
    defer s.p.deinit();
    const p = s.p;
    var name_buf: [4200]u8 = undefined;
    pardes.look.lookAt(p, 0, s.dir);
    p.sync();
    const sub_name = try std.fmt.bufPrint(&name_buf, "{s}/sub/", .{s.dir});
    pardes.look.lookAt(p, p.active, sub_name);
    p.sync();
    const sub = named(p, sub_name).id.?;
    try testing.expectEqualStrings(sub_name[0 .. sub_name.len - 1], p.execDir(sub));
    _ = @import("ninep/pane.zig").appendErrors(p, sub, "oops\n");
    var errors_buf: [4200]u8 = undefined;
    try testing.expect(named(p, try std.fmt.bufPrint(&errors_buf, "{s}{s}", .{ sub_name, config.errors_buffer })).id != null);
}

test "DirLook terminal: a look at a directory opens a terminal there, no pane listing it" {
    if (comptime !pardes.hosted) return;
    var tmp = testing.tmpDir(.{});
    defer tmp.cleanup();
    var buf: [4096]u8 = undefined;
    const s = try session(&tmp, &buf);
    defer s.p.deinit();
    const p = s.p;
    try testing.expect(p.executeBuiltinLine(0, "DirLook terminal"));
    try testing.expectEqual(config.Runtime.DirLook.terminal, p.settings.dir_look);
    pardes.look.lookAt(p, 0, s.dir);
    p.sync();
    var name_buf: [4200]u8 = undefined;
    try testing.expectEqual(@as(usize, 0), named(p, try std.fmt.bufPrint(&name_buf, "{s}/", .{s.dir})).count);
    try testing.expect(p.panes[p.active].?.isTerminal());
    try testing.expectEqualStrings(s.dir, p.panes[p.active].?.cwdSlice());
    // Bare, it steps back to pane, the default.
    try testing.expect(p.executeBuiltinLine(0, "DirLook"));
    try testing.expectEqual(config.Runtime.DirLook.pane, p.settings.dir_look);
}

test "over 9P a directory pane is a text pane whose name ends in /, its body the listing, ctl's isdir 1, and get reads it again" {
    if (comptime !pardes.hosted) return;
    const th = @import("ninep/testing.zig");
    const tree = @import("ninep/tree.zig");
    var tmp = testing.tmpDir(.{});
    defer tmp.cleanup();
    var buf: [4096]u8 = undefined;
    const s = try session(&tmp, &buf);
    defer s.p.deinit();
    const p = s.p;
    var line_buf: [4200]u8 = undefined;
    _ = th.wr(p, @intFromEnum(tree.TopFile.look), try std.fmt.bufPrint(&line_buf, "{s}\n", .{s.dir}));
    p.sync();
    const pane = p.panes[p.active].?;
    const index = th.rd(p, @intFromEnum(tree.TopFile.index), 0, 8192).bytes;
    try testing.expect(std.mem.indexOf(u8, index, try std.fmt.bufPrint(&line_buf, "{d} text 0 {s}/ ", .{ pane.serial, s.dir })) != null);
    try testing.expectEqualStrings(".dot     sub/     top.txt\n", th.rd(p, tree.Node.of(pane.serial, .body), 0, 4096).bytes);
    var fields = std.mem.tokenizeScalar(u8, th.rd(p, tree.Node.of(pane.serial, .ctl), 0, 4096).bytes, ' ');
    for (0..3) |_| _ = fields.next();
    try testing.expectEqualStrings("1", fields.next().?);
    try tmp.dir.writeFile(testing.io, .{ .sub_path = "zz", .data = "" });
    try testing.expectEqual(tree.Status.ok, th.wr(p, tree.Node.of(pane.serial, .ctl), "get\n").reply.status);
    const after = th.rd(p, tree.Node.of(pane.serial, .body), 0, 4096).bytes;
    try testing.expect(std.mem.indexOf(u8, after, "zz") != null);
    try testing.expectEqualStrings(pane.file.?.content, after);
}

test "a directory pane lays its entries out again when its width changes, unless its text was edited" {
    if (comptime !pardes.hosted) return;
    var tmp = testing.tmpDir(.{});
    defer tmp.cleanup();
    var buf: [4096]u8 = undefined;
    const s = try session(&tmp, &buf);
    defer s.p.deinit();
    const p = s.p;
    pardes.look.lookAt(p, 0, s.dir);
    p.sync();
    const pane = p.panes[p.active].?;
    // 9 cells a column: two of them want 18 cells and the line numbers.
    fit(p, pane, 24);
    try testing.expectEqualStrings(".dot     top.txt\nsub/\n", pane.file.?.content);
    fit(p, pane, 80);
    try testing.expectEqualStrings(".dot     sub/     top.txt\n", pane.file.?.content);
    try testing.expect(p.executeBuiltinLine(p.active, "Edit 1d"));
    const edited = try testing.allocator.dupe(u8, pane.file.?.content);
    defer testing.allocator.free(edited);
    fit(p, pane, 24);
    try testing.expectEqualStrings(edited, pane.file.?.content);
}