//! The tags (acme's tag half of wind.c): a pane's computed prefix and its
//! default and saved tails, going into a tag and out again, the path drafted
//! as a new name, and the column and workspace tags above the panes.
const pardes = @import("pardes.zig");
const std = @import("std");
const modal = @import("modal.zig");
const ctlfs = @import("ninep/tree.zig");
const panes = @import("panes.zig");
const edit = @import("edit.zig");
const exec = @import("exec.zig");
const config = @import("config.zig");
const pdf_enabled = panes.Pdf.enabled;
const dump = @import("dump.zig");
const Pane = panes.Pane;
const Text = panes.Text;
const TAG_TEXT_INSET = pardes.TAG_TEXT_INSET;
const Pardes = pardes.Pardes;

pub const pane_tail = " " ++ config.pane_builtins_str;
pub const pdf_pane_tail = " " ++ config.pdf_pane_builtins_str;
pub const file_pane_tail = " " ++ config.file_pane_builtins_str;
pub const context_pane_tail = file_pane_tail ++ " TreeContext";
pub const locations_pane_tail = file_pane_tail ++ " LocationsConfig";
pub const terminal_pane_tail = " " ++ config.terminal_pane_builtins_str;
pub const command_pane_tail = " " ++ config.command_pane_builtins_str;
/// A file with changes it has not saved.
pub fn dirty(pane: *const panes.Pane) bool {
    const f = pane.file orelse return false;
    return panes.Output.fileTraits(f.output).saves and (f.revision != f.saved_revision or f.disk_gone);
}
/// What a column's tag says until someone edits it.
pub const column_tag_default = "New Tty Find Grep Joincol Delcol";

/// What a header says until someone edits it: for the workspace the
/// fixed builtins, plus `Restore <path>` once a dump exists.
pub fn headerDefault(p: *Pardes, what: Text.What) []const u8 {
    if (what == .column) return column_tag_default;
    const d = p.last_dump orelse return config.topbar_str;
    return std.fmt.allocPrint(p.scratch.allocator(), config.topbar_str ++ " Restore {s}", .{d}) catch config.topbar_str;
}

/// the topbar line -- render and click dispatch must agree on this exact
/// string
pub fn topbar(p: *Pardes) []const u8 {
    return p.global_tag.own orelse headerDefault(p, .workspace);
}

pub fn columnTag(p: *const Pardes, c: usize) []const u8 {
    return p.col_tags[c].own orelse column_tag_default;
}

/// The header with the keyboard, when one has it.
pub fn focusedHeader(p: *Pardes) ?*Text {
    if (!p.header_focus) return null;
    if (p.header_column) |c| return if (c < p.ncol) &p.col_tags[c] else null;
    return &p.global_tag;
}

pub fn revealHeader(p: *Pardes) void {
    const t = focusedHeader(p) orelse {
        p.header_scroll = 0;
        p.header_top = 0;
        return;
    };
    const text = edit.flatSurface(p, t) catch return;
    const cur: usize = @intCast(@max(0, t.cur_row));
    const rows: usize = if (p.header_column != null) p.columnBarHeight() else p.topBarHeight();
    if (cur < p.header_top) p.header_top = cur;
    if (rows > 0 and cur >= p.header_top + rows) p.header_top = cur + 1 - rows;
    const line = modal.lineSlice(text, cur);
    const width = p.tagCapacity(if (p.header_column) |c| p.col_w[c] -| TAG_TEXT_INSET else p.screen_w);
    const col = panes.File.rawDisplayCol(line, @min(@as(usize, @intCast(@max(0, t.cur_col))), line.len));
    if (col < p.header_scroll) p.header_scroll = col;
    if (col >= p.header_scroll + width) p.header_scroll = col -| (width -| 1);
    var raw = panes.File.rawAtDisplay(line, p.header_scroll);
    p.header_scroll = panes.File.rawDisplayCol(line, raw);
    if (width > 0 and col >= p.header_scroll + width) {
        raw = modal.nextGrapheme(line, raw);
        p.header_scroll = panes.File.rawDisplayCol(line, raw);
    }
}

/// A terminal's directory as its tag shows it: one line, as /index shows
/// it (a newline `\n`), never a raw newline breaking the tag.
fn shownDir(arena: std.mem.Allocator, pane: *Pane) ![]const u8 {
    const dir = pane.cwdSlice();
    if (std.mem.indexOfAny(u8, dir, "\n\\\x7f") == null and for (dir) |c| {
        if (c < ' ') break false;
    } else true) return dir;
    const out = try arena.alloc(u8, dir.len * 4 + 4);
    return pardes.ctlfs.events.shown(dir, out);
}

/// The computed start of a pane's tag -- its path and dirty marker, a
/// PDF's page, a terminal's directory -- without the space that parts it
/// from the tag's own text. It is never stored, and never edited.
pub fn pathPrefix(arena: std.mem.Allocator, pane: *Pane) ![]const u8 {
    if (comptime pdf_enabled) if (pane.pdf) |pv|
        return std.fmt.allocPrint(arena, "{s} [{d}/{d}]", .{ pv.path, pv.page + 1, pv.page_count });
    if (pane.image) |*state| return panes.Image.tagPrefix(arena, state);
    // A command pane: its directory, the line it runs, and how that went.
    // Its first line only, cut to 48 bytes at a character's start: a tag's
    // first row is where the prefix ends, and a line that ran over to a
    // second (acme runs a multi-line selection as one command) would move
    // it (body_layer.zig tagTintRange).
    if (pane.command) |line| {
        const first = line[0 .. std.mem.indexOfAny(u8, line, "\r\n") orelse line.len];
        var cut = @min(first.len, 48);
        while (cut < first.len and cut > 0 and first[cut] & 0xC0 == 0x80) cut -= 1;
        const shown = first[0..cut];
        const more = if (shown.len < line.len) "..." else "";
        var idbuf: [48]u8 = undefined;
        const id = exec.replId(&idbuf, pane);
        const gap = if (id.len > 0) " " else "";
        if (!pane.command_done) return std.fmt.allocPrint(arena, "{s} ({s}{s}) running{s}{s}", .{ (try shownDir(arena, pane)), shown, more, gap, id });
        if (pane.command_status) |n| return std.fmt.allocPrint(arena, "{s} ({s}{s}) exit {d}{s}{s}", .{ (try shownDir(arena, pane)), shown, more, n, gap, id });
        return std.fmt.allocPrint(arena, "{s} ({s}{s}) exit ?{s}{s}", .{ (try shownDir(arena, pane)), shown, more, gap, id });
    }
    // A bound REPL says what it is bound as, beside its Tty word.
    if (pane.repl != null) {
        var idbuf: [48]u8 = undefined;
        return std.fmt.allocPrint(arena, "{s} {s}", .{ (try shownDir(arena, pane)), exec.replId(&idbuf, pane) });
    }
    // Unsaved text shows on the grip, as acme's modbutton does, not as a
    // mark in the text: the prefix is the name alone.
    if (pane.file) |f| return if (pane.prompt == .name) pane.input.own orelse f.path else f.path;
    return (try shownDir(arena, pane));
}

pub fn tagPrefix(p: *Pardes, pane: *Pane) ![]u8 {
    return prefixIn(p.scratch.allocator(), pane);
}

/// The prefix as the tag shows it, built in `arena`.
pub fn prefixIn(arena: std.mem.Allocator, pane: *Pane) ![]u8 {
    const prefix = try pathPrefix(arena, pane);
    // The space between the prefix and the tag's own text is the text's
    // (every default starts with one), but the prefix is computed, so it
    // cannot trust the text to keep it: with it deleted, Look and Exec
    // would see the path and the first word as one. The prefix brings its
    // own then.
    const tail = curTail(pane);
    if (tail.len > 0 and std.mem.indexOfScalar(u8, " \t\n", tail[0]) == null)
        return std.fmt.allocPrint(arena, "{s} ", .{prefix});
    return arena.dupe(u8, prefix);
}

/// The tag's own text: what the user made of it, or until then the
/// default a pane of its kind starts with.
pub fn curTail(pane: *Pane) []const u8 {
    return pane.tag.own orelse defaultTail(pane);
}

pub fn defaultTail(pane: *const Pane) []const u8 {
    if (comptime pdf_enabled) if (pane.pdf != null) return pdf_pane_tail;
    if (pane.file) |file| if (file.output) |out|
        if (panes.Output.usesLocationsConfig(out.from)) return locations_pane_tail;
    if (panes.File.supportsContext(pane)) return context_pane_tail;
    if (pane.file != null) return file_pane_tail;
    if (pane.command != null) return command_pane_tail;
    if (pane.isTerminal()) return if (pane.shell_tail_len > 0) pane.shell_tail[0..pane.shell_tail_len] else terminal_pane_tail;
    return pane_tail;
}

/// The tag as it is shown, read and pointed at: its computed prefix and
/// its own text after it.
pub fn tagText(p: *Pardes, arena: std.mem.Allocator, pane: *Pane) ![]u8 {
    const prefix = try tagPrefix(p, pane);
    const tail = curTail(pane);
    const out = try arena.alloc(u8, prefix.len + tail.len);
    @memcpy(out[0..prefix.len], prefix);
    @memcpy(out[prefix.len..], tail);
    return out;
}

/// Give the keyboard to the tag in normal mode (`:`), its cursor where
/// the tag last had it. The first time there is nothing to remember, and
/// it starts on Save, so that `:` and the execute key write the file.
pub fn enterTag(p: *Pardes, pane: *Pane) void {
    const t = &pane.tag;
    const whole = tagText(p, p.scratch.allocator(), pane) catch return;
    if (!t.cur_pinned) {
        // Save is looked for in the tag's own text, after the prefix.
        const lead = whole.len - curTail(pane).len;
        const tail = whole[lead..];
        var words = std.mem.tokenizeAny(u8, tail, " \t\n");
        const at = lead + while (words.next()) |word| {
            if (std.mem.eql(u8, word, "Save")) break @intFromPtr(word.ptr) - @intFromPtr(tail.ptr);
        } else tail.len - std.mem.trimStart(u8, tail, " ").len;
        const cursor = modal.positionAt(whole, @min(at, whole.len));
        t.cur_row = @intCast(cursor.row);
        t.cur_col = @intCast(cursor.col);
        t.cur_pinned = true;
    }
    // The text may have changed since (a 9P write, a rename), so the
    // remembered cursor is pulled back inside it. It is the cursor that
    // is remembered, not a selection.
    const rows = modal.cursorLineCount(whole);
    t.cur_row = @intCast(@min(@as(usize, @intCast(@max(0, t.cur_row))), rows - 1));
    const line = modal.lineSlice(whole, @intCast(t.cur_row));
    t.cur_col = @intCast(modal.graphemeStart(line, @min(line.len, @as(usize, @intCast(@max(0, t.cur_col))))));
    t.vsel.active = false;
    t.msel.active = false;
    t.nsel = 0;
    t.select = false;
    t.restore_cursor = false;
    t.sticky_col = -1;
    t.mode = .normal;
    t.normal.clear();
    pane.focus = .tag;
}

/// A pane's tag as it is shown: its lines, each wrapped onto more rows at
/// the tag's width as acme's frame wraps a tag at its right edge (plan9port
/// acme wind.c:140, wintaglines, counts the frame's lines). `soft` are the
/// offsets in `text` of the newlines the wrapping put in.
pub const Shown = struct {
    text: []u8,
    soft: []const usize,

    /// The tag's own offset of a shown one.
    pub fn toReal(s: Shown, off: usize) usize {
        var n: usize = 0;
        for (s.soft) |b| {
            if (b < off) n += 1 else break;
        }
        return off - n;
    }

    /// The shown offset of the tag's own one.
    pub fn fromReal(s: Shown, real: usize) usize {
        var off = real;
        for (s.soft) |b| {
            if (b <= off) off += 1 else break;
        }
        return off;
    }

    pub fn rows(s: Shown) usize {
        return modal.cursorLineCount(s.text);
    }
};

/// `whole` wrapped at `width` display columns.
pub fn wrapTag(arena: std.mem.Allocator, whole: []const u8, width: usize) !Shown {
    var out: std.ArrayList(u8) = .empty;
    var soft: std.ArrayList(usize) = .empty;
    const w = @max(1, width);
    var lines = std.mem.splitScalar(u8, whole, '\n');
    var first = true;
    while (lines.next()) |line| {
        if (!first) try out.append(arena, '\n');
        first = false;
        var rest = line;
        while (panes.File.displayWidth(rest) > w) {
            var cut = modal.graphemeStart(rest, panes.File.rawAtDisplay(rest, w));
            if (cut == 0) cut = modal.nextGrapheme(rest, 0);
            try out.appendSlice(arena, rest[0..cut]);
            try soft.append(arena, out.items.len);
            try out.append(arena, '\n');
            rest = rest[cut..];
        }
        try out.appendSlice(arena, rest);
    }
    return .{ .text = out.items, .soft = soft.items };
}

/// The tag's width for wrapping: all its columns. A row the text fills
/// exactly stays one row, as acme's frame wraps a box only when it is wider
/// than what is left (libframe frutil.c _frcklinewrap), and the caret past
/// its end sits at the edge (frptofchar.c clamps it to r.max.x).
pub fn tagWidth(p: *const Pardes, id: usize) usize {
    return @max(1, @as(usize, p.tagCapacity(p.rects[id].w -| TAG_TEXT_INSET)));
}

pub fn shownTag(p: *Pardes, arena: std.mem.Allocator, pane: *Pane) !Shown {
    const whole = try tagText(p, arena, pane);
    const id = p.paneIdOf(pane) orelse return .{ .text = whole, .soft = &.{} };
    return wrapTag(arena, whole, tagWidth(p, id));
}

/// Where display column `col` of the tag's shown row `row` puts its
/// cursor: the tag as shown, prefix and all, wrapped rows included.
pub fn tagOffsetAt(p: *Pardes, pane: *Pane, row: usize, col: usize) ?modal.Cursor {
    const arena = p.scratch.allocator();
    const shown = shownTag(p, arena, pane) catch return null;
    const whole = tagText(p, arena, pane) catch return null;
    const at = row + pane.tag_top;
    const line = modal.lineSlice(shown.text, at);
    const off = modal.lineStartOffset(shown.text, at) + modal.graphemeStart(line, panes.File.rawAtDisplay(line, col));
    return modal.positionAt(whole, @min(shown.toReal(off), whole.len));
}

/// Whether display column `col` of the tag's shown row `row` is on a name
/// a click drafts: a saving file's path.
pub fn onName(pane: *Pane, row: usize, col: usize) bool {
    if (row + pane.tag_top != 0) return false;
    const f = pane.file orelse return false;
    if (!panes.Output.fileTraits(f.output).saves) return false;
    const name = if (pane.prompt == .name) pane.input.own orelse f.path else f.path;
    return col < panes.File.displayWidth(name);
}

/// A key typed into a saving file's path, with the tag's cursor there,
/// drafts a new name as a click on it does: the path is computed, so it is
/// never the tag's own text to edit, but a buffer's name can be drafted.
/// True when it did.
pub fn typedIntoName(p: *Pardes, pane: *Pane, key: pardes.Key) bool {
    const f = pane.file orelse return false;
    if (!panes.Output.fileTraits(f.output).saves or pane.tag.cur_row != 0) return false;
    const at: usize = @intCast(@max(0, pane.tag.cur_col));
    const back = key.cp == pardes.Key.backspace or pardes.hit(key, config.insert_backspace_alias);
    const forward = key.cp == pardes.Key.delete or pardes.hit(key, config.insert_delete_alias);
    const typed = key.text.len > 0 and !key.ctrl and !key.alt;
    const inside = if (back) at > 0 and at <= f.path.len else if (forward or typed) at < f.path.len else false;
    if (!inside) return false;
    draftName(p, pane, panes.File.displayWidth(f.path[0..at]));
    edit.handleInsert(p, &pane.input, key);
    return true;
}

/// Start a name draft for a file that can take one, its caret at display
/// column `col` of the path. Nothing changes until it is typed into.
pub fn draftName(p: *Pardes, pane: *Pane, col: usize) void {
    const f = pane.file orelse return;
    if (!panes.Output.fileTraits(f.output).saves) return;
    const name = p.gpa.dupe(u8, f.path) catch return;
    pane.closePrompt();
    pane.prompt = .name;
    pane.input = .{ .what = .input, .own = name, .mode = .insert, .cur_pinned = true, .cur_col = @intCast(@min(name.len, panes.File.rawAtDisplay(name, col))) };
}

/// Commit a drafted buffer name, never a disk rename or write. Keep the
/// draft visible on failure so the user can correct it or cancel with Esc.
pub fn commitTagName(p: *Pardes, pane: *Pane) bool {
    if (pane.prompt != .name) return true;
    const id = p.paneIdOf(pane) orelse return false;
    const name = pane.input.own orelse "";
    if (name.len == 0 or name[name.len - 1] == '/' or !std.unicode.utf8ValidateSlice(name)) {
        p.reportError(id, "name", error.InvalidName);
        return false;
    }
    for (name) |byte| if (byte < ' ') {
        p.reportError(id, "name", error.InvalidName);
        return false;
    };
    var home_buf: [4096]u8 = undefined;
    const full = std.fs.path.resolvePosix(p.scratch.allocator(), &.{ Pardes.paneDir(pane), pardes.filesystem.expandHome(name, &home_buf) }) catch |err| {
        p.reportError(id, "name", err);
        return false;
    };
    ctlfs.pane.nameBuffer(p, id, full, true) catch |err| {
        p.reportError(id, "name", err);
        return false;
    };
    pane.closePrompt();
    return true;
}

pub fn exitHeader(p: *Pardes) void {
    p.header_focus = false;
    p.header_column = null;
    p.header_drag = false;
    p.header_scroll = 0;
    p.header_top = 0;
}

/// Give the keyboard to a column's tag, or the workspace's for null, in
/// normal mode, its cursor where that header last had it.
pub fn enterHeader(p: *Pardes, column: ?usize) void {
    exitHeader(p);
    if (p.panes[p.active]) |pane| pane.focus = .body;
    p.header_focus = true;
    p.header_column = column;
    if (column) |c| p.setActiveColumn(c);
    const t = focusedHeader(p) orelse return exitHeader(p);
    const text = edit.flatSurface(p, t) catch "";
    const rows = modal.cursorLineCount(text);
    t.cur_row = @intCast(@min(@as(usize, @intCast(@max(0, t.cur_row))), rows - 1));
    const line = modal.lineSlice(text, @intCast(t.cur_row));
    t.cur_col = @intCast(modal.graphemeStart(line, @min(line.len, @as(usize, @intCast(@max(0, t.cur_col))))));
    t.cur_pinned = true;
    t.vsel.active = false;
    t.msel.active = false;
    t.nsel = 0;
    t.select = false;
    t.restore_cursor = false;
    t.mode = .normal;
    t.normal.clear();
}

/// A dump's tag tail, what was typed after the name: a dump from 0.0.4 on
/// writes it, and an older one's saved tag is not read.
pub fn restoreDumpTail(p: *Pardes, pane: *Pane, src: dump.Pane) void {
    const tail = src.tag_tail orelse return;
    pane.tag.own = p.gpa.dupe(u8, tail) catch return;
}

/// The span a header's selection covers on line `row` of its text, in
/// that line's bytes: up to the caret while typing, and over the
/// cursor's own cell too in normal mode, where a cursor is a cell.
pub fn headerSelection(t: *const Text, text: []const u8, row: usize) ?struct { lo: usize, hi: usize } {
    if (!t.vsel.active) return null;
    const anchor = modal.offsetAt(text, .{ .row = @intCast(@max(0, t.vsel.row)), .col = @intCast(@max(0, t.vsel.col)) });
    const cursor = modal.offsetAt(text, .{ .row = @intCast(@max(0, t.cur_row)), .col = @intCast(@max(0, t.cur_col)) });
    const lo = @min(anchor, cursor);
    const hi = if (t.mode == .insert) @max(anchor, cursor) else modal.nextGrapheme(text, @max(anchor, cursor));
    const start = modal.lineStartOffset(text, row);
    const end = modal.lineEndOffset(text, row);
    if (hi <= start or lo >= end) return null;
    return .{ .lo = @max(lo, start) - start, .hi = @min(hi, end) - start };
}

/// Column and workspace tags are one line, as acme's: a newline typed,
/// pasted or restored from a dump into one becomes a space, the caret and
/// the selection kept on the same characters.
pub fn flattenHeaders(p: *Pardes) void {
    for (p.col_tags[0..p.ncol]) |*t| flatten(t);
    flatten(&p.global_tag);
}

fn flatten(t: *Text) void {
    const own = t.own orelse return;
    if (std.mem.indexOfScalar(u8, own, '\n') == null) return;
    const cur = modal.offsetAt(own, .{ .row = @intCast(@max(0, t.cur_row)), .col = @intCast(@max(0, t.cur_col)) });
    const anchor = modal.offsetAt(own, .{ .row = @intCast(@max(0, t.vsel.row)), .col = @intCast(@max(0, t.vsel.col)) });
    std.mem.replaceScalar(u8, own, '\n', ' ');
    t.cur_row = 0;
    t.cur_col = @intCast(cur);
    t.vsel.row = 0;
    t.vsel.col = @intCast(anchor);
    t.nsel = 0;
}

test "a column or workspace tag is one line: a newline in it is a space" {
    const p = try Pardes.init(std.testing.allocator, .{ .cols = 50, .rows = 12, .tty_only = true });
    defer p.deinit();
    p.col_tags[0].own = try p.gpa.dupe(u8, "New\nSnarf");
    p.col_tags[0].cur_row = 1;
    p.col_tags[0].cur_col = 2;
    p.global_tag.own = try p.gpa.dupe(u8, "Newcol\nExit");
    p.sync();
    try std.testing.expectEqualStrings("New Snarf", columnTag(p, 0));
    try std.testing.expectEqualStrings("Newcol Exit", p.global_tag.own.?);
    try std.testing.expectEqual(@as(i32, 0), p.col_tags[0].cur_row);
    try std.testing.expectEqual(@as(i32, 6), p.col_tags[0].cur_col);
    try std.testing.expectEqual(pardes.COLBAR_H, p.columnBarHeight());
    try std.testing.expectEqual(pardes.TOPBAR_H, p.topBarHeight());
}

test "a pane tag wraps a long line onto rows, and offsets map both ways" {
    var arena_state = std.heap.ArenaAllocator.init(std.testing.allocator);
    defer arena_state.deinit();
    const shown = try wrapTag(arena_state.allocator(), "/a/b.txt Del Snarf Undo Put\nMore", 10);
    try std.testing.expectEqualStrings("/a/b.txt D\nel Snarf U\nndo Put\nMore", shown.text);
    try std.testing.expectEqual(@as(usize, 4), shown.rows());
    try std.testing.expectEqual(@as(usize, 10), shown.toReal(11)); // the 'e' of Del
    try std.testing.expectEqual(@as(usize, 11), shown.fromReal(10));
}