// 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");

pub const allocator = std.testing.allocator;
pub const expectError = std.testing.expectError;
pub const expectString = std.testing.expectEqualStrings;

const App = @import("app.zig").App;

// Merged std.testing.expectEqual and std.testing.expectString
// can be useful when testing fields of an anytype an you don't know
// exactly how to assert equality
pub fn expectEqual(expected: anytype, actual: anytype) !void {
    switch (@typeInfo(@TypeOf(actual))) {
        .array => |arr| if (arr.child == u8) {
            return std.testing.expectEqualStrings(expected, &actual);
        },
        .pointer => |ptr| {
            if (ptr.child == u8) {
                return std.testing.expectEqualStrings(expected, actual);
            } else if (comptime isStringArray(ptr.child)) {
                return std.testing.expectEqualStrings(expected, actual);
            } else if (ptr.child == []u8 or ptr.child == []const u8) {
                return expectString(expected, actual);
            }
        },
        .@"struct" => |structType| {
            inline for (structType.fields) |field| {
                try expectEqual(@field(expected, field.name), @field(actual, field.name));
            }
            return;
        },
        .optional => {
            if (@typeInfo(@TypeOf(expected)) == .null) {
                return std.testing.expectEqual(null, actual);
            }
            return expectEqual(expected, actual.?);
        },
        .@"union" => |union_info| {
            if (union_info.tag_type == null) {
                @compileError("Unable to compare untagged union values");
            }
            const Tag = std.meta.Tag(@TypeOf(expected));

            const expectedTag = @as(Tag, expected);
            const actualTag = @as(Tag, actual);
            try expectEqual(expectedTag, actualTag);

            inline for (std.meta.fields(@TypeOf(actual))) |fld| {
                if (std.mem.eql(u8, fld.name, @tagName(actualTag))) {
                    try expectEqual(@field(expected, fld.name), @field(actual, fld.name));
                    return;
                }
            }
            unreachable;
        },
        else => {},
    }
    return std.testing.expectEqual(expected, actual);
}

pub fn expectDelta(expected: anytype, actual: anytype, delta: anytype) !void {
    if (@typeInfo(@TypeOf(expected)) == .null) {
        return std.testing.expectEqual(null, actual);
    }

    switch (@typeInfo(@TypeOf(actual))) {
        .optional => {
            if (actual) |value| {
                return expectDelta(expected, value, delta);
            }
            return std.testing.expectEqual(null, expected);
        },
        else => {},
    }

    switch (@typeInfo(@TypeOf(expected))) {
        .optional => {
            if (expected) |value| {
                return expectDelta(value, actual, delta);
            }
            return std.testing.expectEqual(null, actual);
        },
        else => {},
    }

    var diff = expected - actual;
    if (diff < 0) {
        diff = -diff;
    }
    if (diff <= delta) {
        return;
    }

    print("Expected {} to be within {} of {}. Actual diff: {}", .{ expected, delta, actual, diff });
    return error.NotWithinDelta;
}

fn isStringArray(comptime T: type) bool {
    if (!is(.array)(T) and !isPtrTo(.array)(T)) {
        return false;
    }
    return std.meta.Elem(T) == u8;
}

pub const TraitFn = fn (type) bool;
pub fn is(comptime id: std.builtin.TypeId) TraitFn {
    const Closure = struct {
        pub fn trait(comptime T: type) bool {
            return id == @typeInfo(T);
        }
    };
    return Closure.trait;
}

pub fn isPtrTo(comptime id: std.builtin.TypeId) TraitFn {
    const Closure = struct {
        pub fn trait(comptime T: type) bool {
            if (!comptime isSingleItemPtr(T)) return false;
            return id == @typeInfo(std.meta.Child(T));
        }
    };
    return Closure.trait;
}

pub fn isSingleItemPtr(comptime T: type) bool {
    if (comptime is(.pointer)(T)) {
        return @typeInfo(T).pointer.size == .one;
    }
    return false;
}

pub fn print(comptime fmt: []const u8, args: anytype) void {
    if (@inComptime()) {
        @compileError(std.fmt.comptimePrint(fmt, args));
    } else {
        std.debug.print(fmt, args);
    }
}

// dummy opts incase we want to add something, and not have to break all the callers
pub fn app(_: anytype) *App {
    return App.init(allocator, .serve) catch unreachable;
}

pub const Random = struct {
    var instance: ?std.Random.DefaultPrng = null;

    pub fn fill(buf: []u8) void {
        var r = random();
        r.bytes(buf);
    }

    pub fn fillAtLeast(buf: []u8, min: usize) []u8 {
        var r = random();
        const l = r.intRangeAtMost(usize, min, buf.len);
        r.bytes(buf[0..l]);
        return buf;
    }

    pub fn intRange(comptime T: type, min: T, max: T) T {
        var r = random();
        return r.intRangeAtMost(T, min, max);
    }

    pub fn random() std.Random {
        if (instance == null) {
            var seed: u64 = undefined;
            std.posix.getrandom(std.mem.asBytes(&seed)) catch unreachable;
            instance = std.Random.DefaultPrng.init(seed);
            // instance = std.Random.DefaultPrng.init(0);
        }
        return instance.?.random();
    }
};