path: root/src/Mini.zig

//! The Mini minimap: a file drawn four rows to a cell in braille dots.
const panes = @import("panes.zig");
const std = @import("std");
const pardes = @import("pardes.zig");
const exec = @import("exec.zig");
const config = @import("config.zig");
const Pardes = pardes.Pardes;
const modal = @import("modal.zig");
const filesystem = @import("fs.zig");
const syntax = @import("syntax.zig");
const File = panes.File;
const Output = panes.Output;

pub const max_input_bytes = 4 * 1024 * 1024;
pub const max_output_bytes = 4 * 1024 * 1024;

pub const State = struct {
    source: []u8,
    colors: []u8,

    pub fn deinit(state: *State, gpa: std.mem.Allocator) void {
        gpa.free(state.source);
        gpa.free(state.colors);
        state.* = undefined;
    }
};

pub const Result = struct {
    content: []u8,
    colors: []u8,

    pub fn deinit(result: Result, gpa: std.mem.Allocator) void {
        gpa.free(result.content);
        gpa.free(result.colors);
    }
};

const Row = struct {
    text: []const u8 = "",
    base: usize = 0,
    at: usize = 0,
    left: usize = 0,
    ink: bool = false,
    color: u8 = 0,

    fn dot(row: *Row, styles: []const u8) ?u8 {
        if (row.left == 0) {
            if (row.at == row.text.len) return null;
            const end = modal.nextGrapheme(row.text, row.at);
            const grapheme = row.text[row.at..end];
            row.left = File.graphemeDisplayWidth(grapheme);
            const n = std.unicode.utf8ByteSequenceLength(grapheme[0]) catch unreachable;
            const cp = std.unicode.utf8Decode(grapheme[0..n]) catch unreachable;
            const blank = switch (cp) {
                '\t'...'\r', ' ', 0x85, 0xa0, 0x1680, 0x2000...0x200a, 0x2028, 0x2029, 0x202f, 0x205f, 0x3000 => true,
                else => false,
            };
            row.ink = !blank or grapheme.len != n;
            row.color = if (styles.len == 0) 0 else styles[row.base + row.at];
            row.at = end;
        }
        row.left -= 1;
        return if (row.ink) row.color else null;
    }
};

fn render(output: ?Result, source: []const u8, styles: []const u8) !usize {
    if (source.len == 0) return 0;
    const end = source.len - @intFromBool(source[source.len - 1] == '\n');
    var lines = std.mem.splitScalar(u8, source[0..end], '\n');
    var offset: usize = 0;
    while (lines.peek() != null) {
        var rows: [4]Row = @splat(.{});
        for (&rows) |*row| {
            const line = lines.next() orelse break;
            row.text = std.mem.trimEnd(u8, line, "\r");
            row.base = @intFromPtr(line.ptr) - @intFromPtr(source.ptr);
        }
        var spaces: usize = 0;
        while (true) {
            var more = false;
            for (rows) |row| more = more or row.at < row.text.len or row.left > 0;
            if (!more) break;
            const bits = [4][2]u3{ .{ 0, 3 }, .{ 1, 4 }, .{ 2, 5 }, .{ 6, 7 } };
            var mask: u8 = 0;
            var counts: [5]u8 = @splat(0);
            for (&rows, 0..) |*row, y| {
                for (0..2) |x| {
                    if (row.dot(styles)) |color| {
                        mask |= @as(u8, 1) << bits[y][x];
                        counts[color] += 1;
                    }
                }
            }
            if (mask == 0) {
                spaces += 1;
                continue;
            }
            if (spaces + 3 > max_output_bytes - offset) return error.MiniTooLarge;
            var color: u8 = 0;
            var most: u8 = 0;
            for (counts[1..], 1..) |count, i| {
                if (count > most) {
                    color = @intCast(i);
                    most = count;
                }
            }
            if (output) |out| {
                @memset(out.content[offset..][0..spaces], ' ');
                @memset(out.colors[offset..][0..spaces], 0);
                _ = std.unicode.utf8Encode(@as(u21, 0x2800) + mask, out.content[offset + spaces ..][0..3]) catch unreachable;
                @memset(out.colors[offset + spaces ..][0..3], color);
            }
            offset += spaces + 3;
            spaces = 0;
        }
        if (offset == max_output_bytes) return error.MiniTooLarge;
        if (output) |out| {
            out.content[offset] = '\n';
            out.colors[offset] = 0;
        }
        offset += 1;
    }
    return offset;
}

pub fn generate(gpa: std.mem.Allocator, source: []const u8, styles: []const u8) !Result {
    if (source.len > max_input_bytes) return error.MiniTooLarge;
    if (!std.unicode.utf8ValidateSlice(source)) return error.InvalidUtf8;
    if (styles.len != 0 and styles.len != source.len) return error.InvalidMiniColors;
    for (styles) |color| if (color > @intFromEnum(syntax.Syn.comment)) return error.InvalidMiniColors;
    const len = try render(null, source, styles);
    const content = try gpa.alloc(u8, len);
    errdefer gpa.free(content);
    const colors = try gpa.alloc(u8, len);
    errdefer gpa.free(colors);
    const result: Result = .{ .content = content, .colors = colors };
    const written = try render(result, source, styles);
    std.debug.assert(written == len);
    return result;
}

pub fn open(p: *Pardes, id: usize, argument: []const u8) !void {
    const caller = p.panes[id] orelse return error.MissingPane;
    const word = std.mem.trim(u8, argument, " \t\r\n");
    if (word.len == 0) return error.MissingPath;
    var path_buf: [4096]u8 = undefined;
    const target = filesystem.resolve(p, word, Pardes.paneDir(caller), &path_buf) orelse return error.FileNotFound;
    if (target.dir) return error.NotAFile;
    const source = try p.gpa.dupe(u8, target.path);
    errdefer p.gpa.free(source);
    const input = try filesystem.readLimit(p, source, max_input_bytes);
    defer p.gpa.free(input);
    const styles = try syntax.highlightFileRange(p.tree_sitter_gpa, source, input, 0, input.len);
    defer p.tree_sitter_gpa.free(styles);
    const result = try generate(p.gpa, input, styles);
    errdefer result.deinit(p.gpa);
    for (p.panes, 0..) |slot, i| {
        const pane = slot orelse continue;
        const file = if (pane.file) |*f| f else continue;
        const old = file.mini orelse continue;
        if (!std.mem.eql(u8, old.source, source)) continue;
        if (std.mem.eql(u8, file.content, result.content) and std.mem.eql(u8, old.colors, result.colors)) {
            p.gpa.free(source);
            result.deinit(p.gpa);
        } else {
            File.setContent(p, file, result.content);
            file.mini = .{ .source = source, .colors = result.colors };
            file.syntax_dirty = false;
            Output.resetBody(p, pane);
        }
        p.active = i;
        return;
    }
    const free = p.freeSlot() orelse return error.NoPaneSlots;
    const dir = std.fs.path.dirname(source) orelse "/";
    const path = try std.fmt.allocPrint(p.gpa, "{s}/Mini {s}", .{ std.mem.trimEnd(u8, dir, "/"), std.fs.path.basename(source) });
    errdefer p.gpa.free(path);
    const history = try File.History.create(p.gpa);
    errdefer p.gpa.destroy(history);
    const pane = try p.newDocPane(free);
    pane.file = .{
        .path = path,
        .content = result.content,
        .output = .{ .from = .{ .cmd = .Mini } },
        .mini = .{ .source = source, .colors = result.colors },
        .history = history,
        .syntax_dirty = false,
    };
    pane.cur_pinned = true;
    exec.placeDoc(p, id, free, pane);
    p.active = free;
}

test "Mini maps every braille dot and partial line group" {
    const gpa = std.testing.allocator;
    const bits = [4][2]u3{ .{ 0, 3 }, .{ 1, 4 }, .{ 2, 5 }, .{ 6, 7 } };
    for (0..256) |mask| {
        var source: [12]u8 = undefined;
        for (0..4) |row| {
            for (0..2) |col| source[row * 3 + col] = if (mask & (@as(usize, 1) << bits[row][col]) != 0) 'x' else ' ';
            source[row * 3 + 2] = '\n';
        }
        const result = try generate(gpa, &source, "");
        defer result.deinit(gpa);
        var expected: [4]u8 = undefined;
        const len: usize = if (mask == 0) 0 else try std.unicode.utf8Encode(@as(u21, 0x2800) + @as(u21, @intCast(mask)), &expected);
        expected[len] = '\n';
        try std.testing.expectEqualStrings(expected[0 .. len + 1], result.content);
        try std.testing.expectEqual(result.content.len, result.colors.len);
        for (result.colors) |color| try std.testing.expectEqual(@as(u8, 0), color);
    }
    for ([_]struct { source: []const u8, expected: []const u8 }{
        .{ .source = "", .expected = "" },
        .{ .source = "x", .expected = "⠁\n" },
        .{ .source = "xx\n", .expected = "⠉\n" },
        .{ .source = "x    \n", .expected = "⠁\n" },
        .{ .source = "\n\n\n\nx", .expected = "\n⠁\n" },
        .{ .source = "x\r\nx\r\n", .expected = "⠃\n" },
    }) |case| {
        const result = try generate(gpa, case.source, "");
        defer result.deinit(gpa);
        try std.testing.expectEqualStrings(case.expected, result.content);
    }
}

test "Mini uses display cells for tabs combining text and wide characters" {
    const gpa = std.testing.allocator;
    for ([_]struct { source: []const u8, expected: []const u8 }{
        .{ .source = "e\u{301}界\n", .expected = "⠉⠁\n" },
        .{ .source = "　x\n", .expected = " ⠁\n" },
        .{ .source = "\u{a0}x\n", .expected = "⠈\n" },
    }) |case| {
        const result = try generate(gpa, case.source, "");
        defer result.deinit(gpa);
        try std.testing.expectEqualStrings(case.expected, result.content);
    }
    const tabs = try generate(gpa, "\tx\n", "");
    defer tabs.deinit(gpa);
    const spaces = config.tab_width / 2;
    for (tabs.content[0..spaces]) |byte| try std.testing.expectEqual(@as(u8, ' '), byte);
    try std.testing.expectEqualStrings(if (config.tab_width % 2 == 0) "⠁\n" else "⠈\n", tabs.content[spaces..]);
}

test "Mini chooses highlighted dots over plain ink with stable color ties" {
    const gpa = std.testing.allocator;
    const source = "xx\nxx\nxx\nxx\n";
    var styles: [source.len]u8 = @splat(0);
    styles[0] = @intFromEnum(syntax.Syn.keyword);
    const rare = try generate(gpa, source, &styles);
    defer rare.deinit(gpa);
    try std.testing.expectEqualStrings("⣿\n", rare.content);
    try std.testing.expectEqualSlices(u8, &.{ 1, 1, 1, 0 }, rare.colors);
    styles[0] = @intFromEnum(syntax.Syn.string);
    styles[1] = @intFromEnum(syntax.Syn.number);
    const tied = try generate(gpa, source, &styles);
    defer tied.deinit(gpa);
    try std.testing.expectEqualSlices(u8, &.{ 2, 2, 2, 0 }, tied.colors);
    styles[3] = @intFromEnum(syntax.Syn.number);
    const majority = try generate(gpa, source, &styles);
    defer majority.deinit(gpa);
    try std.testing.expectEqualSlices(u8, &.{ 3, 3, 3, 0 }, majority.colors);
}

test "Mini generation bounds and allocation failures leave no partial result" {
    const Case = struct {
        fn run(gpa: std.mem.Allocator) !void {
            const result = try generate(gpa, "alpha\nbeta\ngamma\ndelta\nepsilon\n", "");
            defer result.deinit(gpa);
        }
    };
    try std.testing.checkAllAllocationFailures(std.testing.allocator, Case.run, .{});
    try std.testing.expectError(error.InvalidMiniColors, generate(std.testing.allocator, "x", &.{5}));
    try std.testing.expectError(error.InvalidMiniColors, generate(std.testing.allocator, "xx", &.{0}));
    var allocator = std.testing.FailingAllocator.init(std.testing.allocator, .{ .fail_index = 0 });
    const source = try std.testing.allocator.alloc(u8, max_input_bytes + 1);
    defer std.testing.allocator.free(source);
    try std.testing.expectError(error.MiniTooLarge, generate(allocator.allocator(), source, ""));
    for (source[0..max_input_bytes], 0..) |*byte, i| byte.* = if (i % 2 == 0) 'x' else ' ';
    try std.testing.expectError(error.MiniTooLarge, generate(allocator.allocator(), source[0..max_input_bytes], ""));
    try std.testing.expect(!allocator.has_induced_failure);
}

test "Mini publishes only complete snapshots and content replacement drops metadata" {
    const Case = struct {
        fn run(gpa: std.mem.Allocator, path: []const u8) !void {
            const p = try Pardes.init(gpa, .{ .tty_only = true });
            defer p.deinit();
            const source = try p.setTestFile("untouched\n");
            const free = p.freeSlot();
            open(p, 0, path) catch |err| {
                try std.testing.expectEqual(@as(usize, 0), p.active);
                try std.testing.expectEqual(free, p.freeSlot());
                try std.testing.expectEqual(source, p.panes[0].?);
                try std.testing.expectEqualStrings("untouched\n", source.file.?.content);
                return err;
            };
            const file = &p.panes[p.active].?.file.?;
            try std.testing.expectEqualStrings("⠉\n", file.content);
            try std.testing.expectEqualStrings(path, file.mini.?.source);
            const replacement = try gpa.dupe(u8, "plain\n");
            File.setContent(p, file, replacement);
            try std.testing.expect(file.mini == null);
            try std.testing.expectEqualStrings("plain\n", file.content);
        }
    };
    var tmp = std.testing.tmpDir(.{});
    defer tmp.cleanup();
    try tmp.dir.writeFile(std.testing.io, .{ .sub_path = "mini.txt", .data = "xx\n" });
    var dir_buf: [4096]u8 = undefined;
    const dir = dir_buf[0..try tmp.dir.realPath(std.testing.io, &dir_buf)];
    var path_buf: [4096]u8 = undefined;
    const path = try std.fmt.bufPrint(&path_buf, "{s}/mini.txt", .{dir});
    try std.testing.checkAllAllocationFailures(std.testing.allocator, Case.run, .{path});
}