import "@std/mem"
import "@std/testing"

@hide:file
expect_bits proc(text []u8, expected u64) void ! testing.Error {
    value :: parse_float(mem.c_allocator, text) catch |_| { return .expectation_failed }
    try testing.expect_equal(expected, ptrcast!(@u64, &value)^)
}

accepts_signed_decimal_forms_and_exponents test {
    texts [7][]u8 :: ["1", "+1", "01", "1.", ".1e1", "10e-1", "1E+0"]
    for (texts) |text| try testing.expect_equal(f64(1), try parse_float(mem.c_allocator, text))
    try testing.expect_equal(f64(-1.25), try parse_float(mem.c_allocator, "-1.25"))
    try testing.expect_equal(f64(0.5), try parse_float(mem.c_allocator, "+.5"))
    try testing.expect_equal(f64(125), try parse_float(mem.c_allocator, "1.25e+2"))
    try testing.expect_equal(f64(-0.125), try parse_float(mem.c_allocator, "-125E-3"))
}

accepts_borrowed_slices_without_a_terminator test {
    bytes [5]mut u8 := ['x', '1', '.', '5', 'x']
    try testing.expect_equal(f64(1.5), try parse_float(mem.c_allocator, bytes[1..4]))
    try testing.expect_equal(u8('x'), bytes[0])
    try testing.expect_equal(u8('x'), bytes[4])
}

rejects_malformed_or_partially_consumed_input test {
    texts [33][]u8 :: [
        "", "+", "-", ".", "+.", "-.", "e1", ".e1",
        "1e", "1e+", "1e-", "1ee2", "1e1.0", "1.2.3", "--1", "+-1",
        " 1", "1 ", "\t1", "1\n", "1x", "1_0", "1,5", "1\x00", "1\x002",
        "0x1", "0x1p0", "inf", "-Infinity", "nan", "NaN(1)", "\xff", "1\xff",
    ]
    for texts |text| {
        _ = parse_float(mem.c_allocator, text) catch |error| {
            try testing.expect(error == .invalid_number)
            continue
        }
        try testing.expect(false)
    }
}

preserves_signed_zero_even_with_extreme_exponents test {
    positive [4][]u8 :: ["0", "+0.0", "0e999999", "0e-999999"]
    negative [4][]u8 :: ["-0", "-0.0", "-0e999999", "-0e-999999"]
    for positive |text| {
        try expect_bits(text, u64(0))
    }
    for negative |text| {
        try expect_bits(text, maxval!(u64) - u64(9223372036854775807))
    }
}

rounds_decimal_midpoints_to_nearest_even test {
    # IEEE-754 binary64 encodings: 0.1, 1, and the next two values above 1.
    try expect_bits("0.1", u64(4591870180066957722))
    try expect_bits("1.00000000000000011102230246251565404236316680908203125", u64(4607182418800017408))
    try expect_bits("1.00000000000000011102230246251565404236316680908203126", u64(4607182418800017409))
    try expect_bits("1.00000000000000033306690738754696212708950042724609375", u64(4607182418800017410))
    try expect_bits("9007199254740993", u64(4845873199050653696))
}

accepts_finite_representational_boundaries_and_subnormals test {
    # smallest subnormal, largest subnormal, smallest normal, and largest finite binary64.
    try expect_bits("4.9406564584124654e-324", u64(1))
    try expect_bits("2.4703282292062328e-324", u64(1))
    try expect_bits("-4.9406564584124654e-324", maxval!(u64) - u64(9223372036854775806))
    try expect_bits("2.225073858507201e-308", u64(4503599627370495))
    try expect_bits("2.2250738585072014e-308", u64(4503599627370496))
    try expect_bits("1.7976931348623157e308", u64(9218868437227405311))
    try expect_bits("1.7976931348623158e308", u64(9218868437227405311))
    try expect_bits("-1.7976931348623157e308", maxval!(u64) - u64(4503599627370496))
}

rejects_overflow_and_nonzero_underflow_to_zero test {
    texts [12][]u8 :: [
        "1e309", "-1e309", "1.7976931348623159e308", "-1.7976931348623159e308",
        "1e999999", "-1e999999", "1e-999999", "-1e-999999", "1e-324", "-1e-324",
        "2.4703282292062327e-324", "-2.4703282292062327e-324",
    ]
    for texts |text| {
        _ = parse_float(mem.c_allocator, text) catch |error| {
            try testing.expect(error == .out_of_range)
            continue
        }
        try testing.expect(false)
    }
}

@hide:file
AllocationState :: struct {
    remaining usize = maxval!(usize)
    live usize = 0
}

@hide:file
tracked_alloc proc(context ?@mut anyopaque, size usize, alignment usize) ?*mut u8 {
    state @mut AllocationState :: ptrcast!(context?)
    if (state.remaining == 0) return null
    state.remaining -= 1
    memory :: mem.raw_alloc(mem.c_allocator, size, alignment)
    if (memory) |_| state.live += 1
    return memory
}

@hide:file
tracked_realloc proc(context ?@mut anyopaque, memory ?*mut u8, old_size usize, new_size usize, alignment usize) ?*mut u8 {
    state @mut AllocationState :: ptrcast!(context?)
    if (state.remaining == 0) return null
    state.remaining -= 1
    resized :: mem.raw_realloc(mem.c_allocator, memory, old_size, new_size, alignment)
    if (new_size == 0) {
        if (memory) |_| state.live -= 1
    } else if (resized) |_| {
        if (memory) |_| {} else state.live += 1
    }
    return resized
}

@hide:file
tracked_free proc(context ?@mut anyopaque, memory ?*mut u8, size usize, alignment usize) void {
    state @mut AllocationState :: ptrcast!(context?)
    if (memory) |_| state.live -= 1
    mem.raw_free(mem.c_allocator, memory, size, alignment)
}

@hide:file
tracked_vtable :: mem.AllocatorVTable{ alloc = tracked_alloc, realloc = tracked_realloc, free = tracked_free }

releases_temporary_storage_and_propagates_allocation_failure test {
    state := AllocationState{}
    allocator :: mem.Allocator{ context = &state, vtable = &tracked_vtable }
    try testing.expect_equal(f64(1.5), try parse_float(allocator, "1.5"))
    try testing.expect_equal(usize(0), state.live)
    texts [2][]u8 :: ["1e999999", "1e-999999"]
    for texts |text| {
        _ = parse_float(allocator, text) catch |error| {
            try testing.expect(error == .out_of_range)
            try testing.expect_equal(usize(0), state.live)
            continue
        }
        try testing.expect(false)
    }
    state.remaining = 0
    _ = parse_float(allocator, "1.5") catch |error| {
        try testing.expect(error == .out_of_memory)
        try testing.expect_equal(usize(0), state.live)
        return
    }
    try testing.expect(false)
}