// Copyright (C) 2023-2024  Lightpanda (Selecy SAS)
//
// Francis Bouvier <francis@lightpanda.io>
// Pierre Tachoire <pierre@lightpanda.io>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

const std = @import("std");
const builtin = @import("builtin");

const Allocator = std.mem.Allocator;

const BORDER = "=" ** 80;

// use in custom panic handler
var current_test: ?[]const u8 = null;

pub const std_options = std.Options{
    .log_level = .warn,

    // Crypto in Zig is generally slow, but it's particularly slow in debug mode
    // this helps a lot (but it's still slow). Not safe to do this in non-test!
    .side_channels_mitigations = .none,
};

pub var js_runner_duration: usize = 0;
pub var tracking_allocator = TrackingAllocator.init(std.testing.allocator);

pub fn main() !void {
    var mem: [8192]u8 = undefined;
    var fba = std.heap.FixedBufferAllocator.init(&mem);

    const allocator = fba.allocator();

    const env = Env.init(allocator);
    defer env.deinit(allocator);

    var slowest = SlowTracker.init(allocator, 5);
    defer slowest.deinit();

    var args = try std.process.argsWithAllocator(allocator);
    defer args.deinit();

    // ignore the exec name.
    _ = args.next();
    var json_stats = false;
    while (args.next()) |arg| {
        if (std.mem.eql(u8, "--json", arg)) {
            json_stats = true;
            continue;
        }
    }

    var pass: usize = 0;
    var fail: usize = 0;
    var skip: usize = 0;
    var leak: usize = 0;

    Printer.fmt("\r\x1b[0K", .{}); // beginning of line and clear to end of line

    for (builtin.test_functions) |t| {
        if (isSetup(t)) {
            t.func() catch |err| {
                Printer.status(.fail, "\nsetup \"{s}\" failed: {}\n", .{ t.name, err });
                return err;
            };
        }
    }

    for (builtin.test_functions) |t| {
        if (isSetup(t) or isTeardown(t)) {
            continue;
        }

        var status = Status.pass;
        slowest.startTiming();

        const is_unnamed_test = isUnnamed(t);
        if (env.filter) |f| {
            if (!is_unnamed_test and std.mem.indexOf(u8, t.name, f) == null) {
                continue;
            }
        }

        const friendly_name = blk: {
            const name = t.name;
            var it = std.mem.splitScalar(u8, name, '.');
            while (it.next()) |value| {
                if (std.mem.eql(u8, value, "test")) {
                    const rest = it.rest();
                    break :blk if (rest.len > 0) rest else name;
                }
            }
            break :blk name;
        };

        current_test = friendly_name;
        std.testing.allocator_instance = .{};
        const result = t.func();
        current_test = null;

        const ns_taken = slowest.endTiming(friendly_name, is_unnamed_test);

        if (std.testing.allocator_instance.deinit() == .leak) {
            leak += 1;
            Printer.status(.fail, "\n{s}\n\"{s}\" - Memory Leak\n{s}\n", .{ BORDER, friendly_name, BORDER });
        }

        if (result) |_| {
            if (is_unnamed_test == false) {
                pass += 1;
            }
        } else |err| switch (err) {
            error.SkipZigTest => {
                skip += 1;
                status = .skip;
            },
            else => {
                status = .fail;
                fail += 1;
                Printer.status(.fail, "\n{s}\n\"{s}\" - {s}\n{s}\n", .{ BORDER, friendly_name, @errorName(err), BORDER });
                if (@errorReturnTrace()) |trace| {
                    std.debug.dumpStackTrace(trace.*);
                }
                if (env.fail_first) {
                    break;
                }
            },
        }

        if (is_unnamed_test == false) {
            if (env.verbose) {
                const ms = @as(f64, @floatFromInt(ns_taken)) / 1_000_000.0;
                Printer.status(status, "{s} ({d:.2}ms)\n", .{ friendly_name, ms });
            } else {
                Printer.status(status, ".", .{});
            }
        }
    }

    for (builtin.test_functions) |t| {
        if (isTeardown(t)) {
            t.func() catch |err| {
                Printer.status(.fail, "\nteardown \"{s}\" failed: {}\n", .{ t.name, err });
                return err;
            };
        }
    }

    const total_tests = pass + fail;
    const status = if (fail == 0) Status.pass else Status.fail;
    Printer.status(status, "\n{d} of {d} test{s} passed\n", .{ pass, total_tests, if (total_tests != 1) "s" else "" });
    if (skip > 0) {
        Printer.status(.skip, "{d} test{s} skipped\n", .{ skip, if (skip != 1) "s" else "" });
    }
    if (leak > 0) {
        Printer.status(.fail, "{d} test{s} leaked\n", .{ leak, if (leak != 1) "s" else "" });
    }
    Printer.fmt("\n", .{});
    try slowest.display();
    Printer.fmt("\n", .{});

    // TODO: at the very least, `browser` should return real stats
    if (json_stats) {
        var stdout = std.fs.File.stdout();
        var writer = stdout.writer(&.{});
        const stats = tracking_allocator.stats();
        try std.json.Stringify.value(&.{
            .{ .name = "browser", .bench = .{
                .duration = js_runner_duration,
                .alloc_nb = stats.allocation_count,
                .realloc_nb = stats.reallocation_count,
                .alloc_size = stats.allocated_bytes,
            } },
            .{ .name = "libdom", .bench = .{
                .duration = js_runner_duration,
                .alloc_nb = 0,
                .realloc_nb = 0,
                .alloc_size = 0,
            } },
            .{ .name = "v8", .bench = .{
                .duration = js_runner_duration,
                .alloc_nb = 0,
                .realloc_nb = 0,
                .alloc_size = 0,
            } },
            .{ .name = "main", .bench = .{
                .duration = js_runner_duration,
                .alloc_nb = 0,
                .realloc_nb = 0,
                .alloc_size = 0,
            } },
        }, .{ .whitespace = .indent_2 }, &writer.interface);
    }

    std.posix.exit(if (fail == 0) 0 else 1);
}

const Printer = struct {
    fn fmt(comptime format: []const u8, args: anytype) void {
        std.debug.print(format, args);
    }

    fn status(s: Status, comptime format: []const u8, args: anytype) void {
        switch (s) {
            .pass => std.debug.print("\x1b[32m", .{}),
            .fail => std.debug.print("\x1b[31m", .{}),
            .skip => std.debug.print("\x1b[33m", .{}),
            else => {},
        }
        std.debug.print(format ++ "\x1b[0m", args);
    }
};

const Status = enum {
    pass,
    fail,
    skip,
    text,
};

const SlowTracker = struct {
    const SlowestQueue = std.PriorityDequeue(TestInfo, void, compareTiming);
    max: usize,
    slowest: SlowestQueue,
    timer: std.time.Timer,

    fn init(allocator: Allocator, count: u32) SlowTracker {
        const timer = std.time.Timer.start() catch @panic("failed to start timer");
        var slowest = SlowestQueue.init(allocator, {});
        slowest.ensureTotalCapacity(count) catch @panic("OOM");
        return .{
            .max = count,
            .timer = timer,
            .slowest = slowest,
        };
    }

    const TestInfo = struct {
        ns: u64,
        name: []const u8,
    };

    fn deinit(self: SlowTracker) void {
        self.slowest.deinit();
    }

    fn startTiming(self: *SlowTracker) void {
        self.timer.reset();
    }

    fn endTiming(self: *SlowTracker, test_name: []const u8, is_unnamed_test: bool) u64 {
        var timer = self.timer;
        const ns = timer.lap();
        if (is_unnamed_test) {
            return ns;
        }

        var slowest = &self.slowest;

        if (slowest.count() < self.max) {
            // Capacity is fixed to the # of slow tests we want to track
            // If we've tracked fewer tests than this capacity, than always add
            slowest.add(TestInfo{ .ns = ns, .name = test_name }) catch @panic("failed to track test timing");
            return ns;
        }

        {
            // Optimization to avoid shifting the dequeue for the common case
            // where the test isn't one of our slowest.
            const fastest_of_the_slow = slowest.peekMin() orelse unreachable;
            if (fastest_of_the_slow.ns > ns) {
                // the test was faster than our fastest slow test, don't add
                return ns;
            }
        }

        // the previous fastest of our slow tests, has been pushed off.
        _ = slowest.removeMin();
        slowest.add(TestInfo{ .ns = ns, .name = test_name }) catch @panic("failed to track test timing");
        return ns;
    }

    fn display(self: *SlowTracker) !void {
        var slowest = self.slowest;
        const count = slowest.count();
        Printer.fmt("Slowest {d} test{s}: \n", .{ count, if (count != 1) "s" else "" });
        while (slowest.removeMinOrNull()) |info| {
            const ms = @as(f64, @floatFromInt(info.ns)) / 1_000_000.0;
            Printer.fmt("  {d:.2}ms\t{s}\n", .{ ms, info.name });
        }
    }

    fn compareTiming(context: void, a: TestInfo, b: TestInfo) std.math.Order {
        _ = context;
        return std.math.order(a.ns, b.ns);
    }
};

const Env = struct {
    verbose: bool,
    fail_first: bool,
    filter: ?[]const u8,

    fn init(allocator: Allocator) Env {
        return .{
            .verbose = readEnvBool(allocator, "TEST_VERBOSE", true),
            .fail_first = readEnvBool(allocator, "TEST_FAIL_FIRST", false),
            .filter = readEnv(allocator, "TEST_FILTER"),
        };
    }

    fn deinit(self: Env, allocator: Allocator) void {
        if (self.filter) |f| {
            allocator.free(f);
        }
    }

    fn readEnv(allocator: Allocator, key: []const u8) ?[]const u8 {
        const v = std.process.getEnvVarOwned(allocator, key) catch |err| {
            if (err == error.EnvironmentVariableNotFound) {
                return null;
            }
            std.log.warn("failed to get env var {s} due to err {}", .{ key, err });
            return null;
        };
        return v;
    }

    fn readEnvBool(allocator: Allocator, key: []const u8, deflt: bool) bool {
        const value = readEnv(allocator, key) orelse return deflt;
        defer allocator.free(value);
        return std.ascii.eqlIgnoreCase(value, "true");
    }
};

pub const panic = std.debug.FullPanic(struct {
    pub fn panicFn(msg: []const u8, first_trace_addr: ?usize) noreturn {
        if (current_test) |ct| {
            std.debug.print("\x1b[31m{s}\npanic running \"{s}\"\n{s}\x1b[0m\n", .{ BORDER, ct, BORDER });
        }
        std.debug.defaultPanic(msg, first_trace_addr);
    }
}.panicFn);

fn isUnnamed(t: std.builtin.TestFn) bool {
    const marker = ".test_";
    const test_name = t.name;
    const index = std.mem.indexOf(u8, test_name, marker) orelse return false;
    _ = std.fmt.parseInt(u32, test_name[index + marker.len ..], 10) catch return false;
    return true;
}

fn isSetup(t: std.builtin.TestFn) bool {
    return std.mem.endsWith(u8, t.name, "tests:beforeAll");
}

fn isTeardown(t: std.builtin.TestFn) bool {
    return std.mem.endsWith(u8, t.name, "tests:afterAll");
}

pub const TrackingAllocator = struct {
    parent_allocator: Allocator,
    free_count: usize = 0,
    allocated_bytes: usize = 0,
    allocation_count: usize = 0,
    reallocation_count: usize = 0,

    const Stats = struct {
        allocated_bytes: usize,
        allocation_count: usize,
        reallocation_count: usize,
    };

    fn init(parent_allocator: Allocator) TrackingAllocator {
        return .{
            .parent_allocator = parent_allocator,
        };
    }

    pub fn stats(self: *const TrackingAllocator) Stats {
        return .{
            .allocated_bytes = self.allocated_bytes,
            .allocation_count = self.allocation_count,
            .reallocation_count = self.reallocation_count,
        };
    }

    pub fn allocator(self: *TrackingAllocator) Allocator {
        return .{ .ptr = self, .vtable = &.{
            .alloc = alloc,
            .resize = resize,
            .free = free,
            .remap = remap,
        } };
    }

    fn alloc(
        ctx: *anyopaque,
        len: usize,
        alignment: std.mem.Alignment,
        return_address: usize,
    ) ?[*]u8 {
        const self: *TrackingAllocator = @ptrCast(@alignCast(ctx));
        const result = self.parent_allocator.rawAlloc(len, alignment, return_address);
        self.allocation_count += 1;
        self.allocated_bytes += len;
        return result;
    }

    fn resize(
        ctx: *anyopaque,
        old_mem: []u8,
        alignment: std.mem.Alignment,
        new_len: usize,
        ra: usize,
    ) bool {
        const self: *TrackingAllocator = @ptrCast(@alignCast(ctx));
        const result = self.parent_allocator.rawResize(old_mem, alignment, new_len, ra);
        self.reallocation_count += 1; // TODO: only if result is not null?
        return result;
    }

    fn free(
        ctx: *anyopaque,
        old_mem: []u8,
        alignment: std.mem.Alignment,
        ra: usize,
    ) void {
        const self: *TrackingAllocator = @ptrCast(@alignCast(ctx));
        self.parent_allocator.rawFree(old_mem, alignment, ra);
        self.free_count += 1;
    }

    fn remap(
        ctx: *anyopaque,
        memory: []u8,
        alignment: std.mem.Alignment,
        new_len: usize,
        ret_addr: usize,
    ) ?[*]u8 {
        const self: *TrackingAllocator = @ptrCast(@alignCast(ctx));
        const result = self.parent_allocator.rawRemap(memory, alignment, new_len, ret_addr);
        self.reallocation_count += 1; // TODO: only if result is not null?
        return result;
    }
};