package internalwasm

import (
	"math"
	"testing"

	"github.com/stretchr/testify/require"
)

func TestMemoryInstance_HasLen(t *testing.T) {
	memory := &MemoryInstance{Buffer: make([]byte, 100)}

	tests := []struct {
		name        string
		offset      uint32
		sizeInBytes uint64
		expected    bool
	}{
		{
			name:        "simple valid arguments",
			offset:      0, // arbitrary valid offset
			sizeInBytes: 8, // arbitrary valid size
			expected:    true,
		},
		{
			name:        "maximum valid sizeInBytes",
			offset:      memory.Len() - 8,
			sizeInBytes: 8,
			expected:    true,
		},
		{
			name:        "sizeInBytes exceeds the valid size by 1",
			offset:      100, // arbitrary valid offset
			sizeInBytes: uint64(memory.Len() - 99),
			expected:    false,
		},
		{
			name:        "offset exceeds the memory size",
			offset:      memory.Len(),
			sizeInBytes: 1, // arbitrary size
			expected:    false,
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.expected, memory.hasLen(tc.offset, uint32(tc.sizeInBytes)))
		})
	}
}

func TestMemoryInstance_ReadUint32Le(t *testing.T) {
	tests := []struct {
		name       string
		memory     []byte
		offset     uint32
		expected   uint32
		expectedOk bool
	}{
		{
			name:       "valid offset with an endian-insensitive v",
			memory:     []byte{0xff, 0xff, 0xff, 0xff},
			offset:     0, // arbitrary valid offset.
			expected:   math.MaxUint32,
			expectedOk: true,
		},
		{
			name:       "valid offset with an endian-sensitive v",
			memory:     []byte{0xfe, 0xff, 0xff, 0xff},
			offset:     0, // arbitrary valid offset.
			expected:   math.MaxUint32 - 1,
			expectedOk: true,
		},
		{
			name:       "maximum boundary valid offset",
			offset:     1,
			memory:     []byte{0x00, 0x1, 0x00, 0x00, 0x00},
			expected:   1, // arbitrary valid v
			expectedOk: true,
		},
		{
			name:   "offset exceeds the maximum valid offset by 1",
			memory: []byte{0xff, 0xff, 0xff, 0xff},
			offset: 1,
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			memory := &MemoryInstance{Buffer: tc.memory}

			v, ok := memory.ReadUint32Le(tc.offset)
			require.Equal(t, tc.expectedOk, ok)
			require.Equal(t, tc.expected, v)
		})
	}
}

func TestMemoryInstance_ReadUint64Le(t *testing.T) {
	tests := []struct {
		name       string
		memory     []byte
		offset     uint32
		expected   uint64
		expectedOk bool
	}{
		{
			name:       "valid offset with an endian-insensitive v",
			memory:     []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
			offset:     0, // arbitrary valid offset.
			expected:   math.MaxUint64,
			expectedOk: true,
		},
		{
			name:       "valid offset with an endian-sensitive v",
			memory:     []byte{0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
			offset:     0, // arbitrary valid offset.
			expected:   math.MaxUint64 - 1,
			expectedOk: true,
		},
		{
			name:       "maximum boundary valid offset",
			offset:     1,
			memory:     []byte{0x00, 0x1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
			expected:   1, // arbitrary valid v
			expectedOk: true,
		},
		{
			name:   "offset exceeds the maximum valid offset by 1",
			memory: []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
			offset: 1,
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			memory := &MemoryInstance{Buffer: tc.memory}

			v, ok := memory.ReadUint64Le(tc.offset)
			require.Equal(t, tc.expectedOk, ok)
			require.Equal(t, tc.expected, v)
		})
	}
}

func TestMemoryInstance_ReadFloat32Le(t *testing.T) {
	tests := []struct {
		name       string
		memory     []byte
		offset     uint32
		expected   float32
		expectedOk bool
	}{
		{
			name:       "valid offset with an endian-insensitive v",
			memory:     []byte{0xff, 0x00, 0x00, 0xff},
			offset:     0, // arbitrary valid offset.
			expected:   math.Float32frombits(uint32(0xff0000ff)),
			expectedOk: true,
		},
		{
			name:       "valid offset with an endian-sensitive v",
			memory:     []byte{0xfe, 0x00, 0x00, 0xff},
			offset:     0, // arbitrary valid offset.
			expected:   math.Float32frombits(uint32(0xff0000fe)),
			expectedOk: true,
		},
		{
			name:       "maximum boundary valid offset",
			offset:     1,
			memory:     []byte{0x00, 0xcd, 0xcc, 0xcc, 0x3d},
			expected:   0.1, // arbitrary valid v
			expectedOk: true,
		},
		{
			name:   "offset exceeds the maximum valid offset by 1",
			memory: []byte{0xff, 0xff, 0xff, 0xff},
			offset: 1,
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			memory := &MemoryInstance{Buffer: tc.memory}

			v, ok := memory.ReadFloat32Le(tc.offset)
			require.Equal(t, tc.expectedOk, ok)
			require.Equal(t, tc.expected, v)
		})
	}
}

func TestMemoryInstance_ReadFloat64Le(t *testing.T) {
	tests := []struct {
		name       string
		memory     []byte
		offset     uint32
		expected   float64
		expectedOk bool
	}{
		{
			name:       "valid offset with an endian-insensitive v",
			memory:     []byte{0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff},
			offset:     0, // arbitrary valid offset.
			expected:   math.Float64frombits(uint64(0xff000000000000ff)),
			expectedOk: true,
		},
		{
			name:       "valid offset with an endian-sensitive v",
			memory:     []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0x7f},
			offset:     0,               // arbitrary valid offset.
			expected:   math.MaxFloat64, // arbitrary valid v
			expectedOk: true,
		},
		{
			name:       "maximum boundary valid offset",
			offset:     1,
			memory:     []byte{0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0x7f},
			expected:   math.MaxFloat64, // arbitrary valid v
			expectedOk: true,
		},
		{
			name:   "offset exceeds the maximum valid offset by 1",
			memory: []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
			offset: 1,
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			memory := &MemoryInstance{Buffer: tc.memory}

			v, ok := memory.ReadFloat64Le(tc.offset)
			require.Equal(t, tc.expectedOk, ok)
			require.Equal(t, tc.expected, v)
		})
	}
}

func TestMemoryInstance_WriteUint32Le(t *testing.T) {
	memory := &MemoryInstance{Buffer: make([]byte, 100)}

	tests := []struct {
		name          string
		offset        uint32
		v             uint32
		expectedOk    bool
		expectedBytes []byte
	}{
		{
			name:          "valid offset with an endian-insensitive v",
			offset:        0, // arbitrary valid offset.
			v:             math.MaxUint32,
			expectedOk:    true,
			expectedBytes: []byte{0xff, 0xff, 0xff, 0xff},
		},
		{
			name:          "valid offset with an endian-sensitive v",
			offset:        0, // arbitrary valid offset.
			v:             math.MaxUint32 - 1,
			expectedOk:    true,
			expectedBytes: []byte{0xfe, 0xff, 0xff, 0xff},
		},
		{
			name:          "maximum boundary valid offset",
			offset:        memory.Len() - 4, // 4 is the size of uint32
			v:             1,                // arbitrary valid v
			expectedOk:    true,
			expectedBytes: []byte{0x1, 0x00, 0x00, 0x00},
		},
		{
			name:          "offset exceeds the maximum valid offset by 1",
			offset:        memory.Len() - 4 + 1, // 4 is the size of uint32
			v:             1,                    // arbitrary valid v
			expectedBytes: []byte{0xff, 0xff, 0xff, 0xff},
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.expectedOk, memory.WriteUint32Le(tc.offset, tc.v))
			if tc.expectedOk {
				require.Equal(t, tc.expectedBytes, memory.Buffer[tc.offset:tc.offset+4]) // 4 is the size of uint32
			}
		})
	}
}

func TestMemoryInstance_WriteUint64Le(t *testing.T) {
	memory := &MemoryInstance{Buffer: make([]byte, 100)}
	tests := []struct {
		name          string
		offset        uint32
		v             uint64
		expectedOk    bool
		expectedBytes []byte
	}{
		{
			name:          "valid offset with an endian-insensitive v",
			offset:        0, // arbitrary valid offset.
			v:             math.MaxUint64,
			expectedOk:    true,
			expectedBytes: []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
		},
		{
			name:          "valid offset with an endian-sensitive v",
			offset:        0, // arbitrary valid offset.
			v:             math.MaxUint64 - 1,
			expectedOk:    true,
			expectedBytes: []byte{0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
		},
		{
			name:          "maximum boundary valid offset",
			offset:        memory.Len() - 8, // 8 is the size of uint64
			v:             1,                // arbitrary valid v
			expectedOk:    true,
			expectedBytes: []byte{0x1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00},
		},
		{
			name:       "offset exceeds the maximum valid offset by 1",
			offset:     memory.Len() - 8 + 1, // 8 is the size of uint64
			v:          1,                    // arbitrary valid v
			expectedOk: false,
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.expectedOk, memory.WriteUint64Le(tc.offset, tc.v))
			if tc.expectedOk {
				require.Equal(t, tc.expectedBytes, memory.Buffer[tc.offset:tc.offset+8]) // 8 is the size of uint64
			}
		})
	}
}

func TestMemoryInstance_WriteFloat32Le(t *testing.T) {
	memory := &MemoryInstance{Buffer: make([]byte, 100)}

	tests := []struct {
		name          string
		offset        uint32
		v             float32
		expectedOk    bool
		expectedBytes []byte
	}{
		{
			name:          "valid offset with an endian-insensitive v",
			offset:        0, // arbitrary valid offset.
			v:             math.Float32frombits(uint32(0xff0000ff)),
			expectedOk:    true,
			expectedBytes: []byte{0xff, 0x00, 0x00, 0xff},
		},
		{
			name:          "valid offset with an endian-sensitive v",
			offset:        0,                                        // arbitrary valid offset.
			v:             math.Float32frombits(uint32(0xff0000fe)), // arbitrary valid v
			expectedOk:    true,
			expectedBytes: []byte{0xfe, 0x00, 0x00, 0xff},
		},
		{
			name:          "maximum boundary valid offset",
			offset:        memory.Len() - 4, // 4 is the size of float32
			v:             0.1,              // arbitrary valid v
			expectedOk:    true,
			expectedBytes: []byte{0xcd, 0xcc, 0xcc, 0x3d},
		},
		{
			name:          "offset exceeds the maximum valid offset by 1",
			offset:        memory.Len() - 4 + 1, // 4 is the size of float32
			v:             math.MaxFloat32,      // arbitrary valid v
			expectedBytes: []byte{0xff, 0xff, 0xff, 0xff},
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.expectedOk, memory.WriteFloat32Le(tc.offset, tc.v))
			if tc.expectedOk {
				require.Equal(t, tc.expectedBytes, memory.Buffer[tc.offset:tc.offset+4]) // 4 is the size of float32
			}
		})
	}
}

func TestMemoryInstance_WriteFloat64Le(t *testing.T) {
	memory := &MemoryInstance{Buffer: make([]byte, 100)}
	tests := []struct {
		name          string
		offset        uint32
		v             float64
		expectedOk    bool
		expectedBytes []byte
	}{
		{
			name:          "valid offset with an endian-insensitive v",
			offset:        0, // arbitrary valid offset.
			v:             math.Float64frombits(uint64(0xff000000000000ff)),
			expectedOk:    true,
			expectedBytes: []byte{0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff},
		},
		{
			name:          "valid offset with an endian-sensitive v",
			offset:        0,               // arbitrary valid offset.
			v:             math.MaxFloat64, // arbitrary valid v
			expectedOk:    true,
			expectedBytes: []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0x7f},
		},
		{
			name:          "maximum boundary valid offset",
			offset:        memory.Len() - 8, // 8 is the size of float64
			v:             math.MaxFloat64,  // arbitrary valid v
			expectedOk:    true,
			expectedBytes: []byte{0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xef, 0x7f},
		},
		{
			name:       "offset exceeds the maximum valid offset by 1",
			offset:     memory.Len() - 8 + 1, // 8 is the size of float64
			v:          math.MaxFloat64,      // arbitrary valid v
			expectedOk: false,
		},
	}

	for _, tt := range tests {
		tc := tt

		t.Run(tc.name, func(t *testing.T) {
			require.Equal(t, tc.expectedOk, memory.WriteFloat64Le(tc.offset, tc.v))
			if tc.expectedOk {
				require.Equal(t, tc.expectedBytes, memory.Buffer[tc.offset:tc.offset+8]) // 8 is the size of float64
			}
		})
	}
}