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 var ran_webapi_test = false;

var RUNNER: *Runner = undefined;

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

    var gpa: std.heap.DebugAllocator(.{}) = .init;
    var arena = std.heap.ArenaAllocator.init(gpa.allocator());
    defer arena.deinit();

    const allocator = fba.allocator();

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

    var runner = Runner.init(allocator, arena.allocator(), env);
    RUNNER = &runner;
    try runner.run();
}

const Runner = struct {
    env: Env,
    allocator: Allocator,

    // per-test arena, used for collecting substests
    arena: Allocator,
    subtests: std.ArrayListUnmanaged([]const u8),

    fn init(allocator: Allocator, arena: Allocator, env: Env) Runner {
        return .{
            .env = env,
            .arena = arena,
            .subtests = .empty,
            .allocator = allocator,
        };
    }

    pub fn run(self: *Runner) !void {
        var slowest = SlowTracker.init(self.allocator, 5);
        defer slowest.deinit();

        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;
                };
            }
        }

        // If we have a subfilter, Document#query_selector_all
        // Then we have a special check to make sure _some_ test was run. This
        const webapi_html_test_mode = self.env.filter == null and self.env.subfilter != null;

        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 (!is_unnamed_test) {
                if (self.env.filter) |f| {
                    if (std.mem.indexOf(u8, t.name, f) == null) {
                        continue;
                    }
                } else if (webapi_html_test_mode) {
                    // allow filtering by subfilter only, assumes subfilters
                    // only exists for "WebApi: " tests (which is true for now).
                    if (std.mem.indexOf(u8, t.name, "WebApi: ") == 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;
            };
            defer {
                self.subtests = .{};
                const arena: *std.heap.ArenaAllocator = @ptrCast(@alignCast(self.arena.ptr));
                _ = arena.reset(.{ .retain_with_limit = 2048 });
            }

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

            if (webapi_html_test_mode and self.subtests.items.len == 0) {
                continue;
            }

            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) {
                    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", .{ BORDER, friendly_name, @errorName(err) });
                    if (self.subtests.getLastOrNull()) |st| {
                        Printer.status(.fail, " {s}\n", .{st});
                    }
                    Printer.status(.fail, BORDER ++ "\n", .{});
                    if (@errorReturnTrace()) |trace| {
                        std.debug.dumpStackTrace(trace.*);
                    }
                    if (self.env.fail_first) {
                        break;
                    }
                },
            }

            if (!is_unnamed_test) {
                if (self.env.verbose) {
                    const ms = @as(f64, @floatFromInt(ns_taken)) / 1_000_000.0;
                    Printer.status(status, "{s} ({d:.2}ms)\n", .{ friendly_name, ms });
                    for (self.subtests.items) |st| {
                        Printer.status(status, "  - {s} \n", .{st});
                    }
                } 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 (total_tests > 0 and 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", .{});
        std.posix.exit(if (fail == 0) 0 else 1);
    }
};

pub fn shouldRun(name: []const u8) bool {
    const sf = RUNNER.env.subfilter orelse return true;
    return std.mem.indexOf(u8, name, sf) != null;
}

pub fn subtest(name: []const u8) !void {
    try RUNNER.subtests.append(RUNNER.arena, try RUNNER.arena.dupe(u8, name));
}

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,
    subfilter: ?[]const u8,

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

    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");
    }

    fn parseFilter(full_filter: ?[]const u8) struct { ?[]const u8, ?[]const u8 } {
        const ff = full_filter orelse return .{ null, null };
        if (ff.len == 0) return .{ null, null };

        const split = std.mem.indexOfScalarPos(u8, ff, 0, '#') orelse {
            return .{ ff, null };
        };

        const filter = std.mem.trim(u8, ff[0..split], " ");

        return .{
            if (filter.len == 0) null else filter,
            std.mem.trim(u8, ff[split + 1 ..], " "),
        };
    }
};

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", .{ BORDER, ct });
            if (RUNNER.subtests.getLastOrNull()) |st| {
                std.debug.print(" {s}\n", .{st});
            }
            std.debug.print("\x1b[0m{s}\n", .{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");
}