package commands

import (
	"strings"
	"testing"

	"c65gm/internal/compiler"
	"c65gm/internal/preproc"
)

func TestXorCommand_WillHandle(t *testing.T) {
	cmd := &XorCommand{}

	tests := []struct {
		name string
		line string
		want bool
	}{
		{"old syntax WITH/GIVING", "XOR a WITH b GIVING c", true},
		{"old syntax WITH/arrow", "XOR a WITH b -> c", true},
		{"new syntax", "result = x ^ y", true},
		{"not XOR", "ADD a TO b GIVING c", false},
		{"wrong param count", "XOR a b c", false},
		{"empty", "", false},
		{"new syntax wrong op", "result = x + y", false},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			line := preproc.Line{Text: tt.line, Kind: preproc.Source}
			got := cmd.WillHandle(line)
			if got != tt.want {
				t.Errorf("WillHandle() = %v, want %v", got, tt.want)
			}
		})
	}
}

func TestXorCommand_OldSyntax(t *testing.T) {
	tests := []struct {
		name      string
		line      string
		setupVars func(*compiler.SymbolTable)
		wantAsm   []string
		wantErr   bool
	}{
		{
			name: "byte XOR byte -> byte (variables)",
			line: "XOR a WITH b GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0xFF)
				st.AddVar("b", "", compiler.KindByte, 0xAA)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda a",
				"\teor b",
				"\tsta result",
			},
		},
		{
			name: "byte XOR byte -> word",
			line: "XOR a WITH b GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0xFF)
				st.AddVar("b", "", compiler.KindByte, 0xAA)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda a",
				"\teor b",
				"\tsta result",
				"\tlda #0",
				"\tsta result+1",
			},
		},
		{
			name: "word XOR word -> word",
			line: "XOR x WITH y GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("x", "", compiler.KindWord, 0x1234)
				st.AddVar("y", "", compiler.KindWord, 0x5678)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda x",
				"\teor y",
				"\tsta result",
				"\tlda x+1",
				"\teor y+1",
				"\tsta result+1",
			},
		},
		{
			name: "byte XOR literal -> byte",
			line: "XOR a WITH $AA GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0xFF)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda a",
				"\teor #$aa",
				"\tsta result",
			},
		},
		{
			name: "literal XOR byte -> byte",
			line: "XOR 255 WITH b GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("b", "", compiler.KindByte, 0xAA)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda #$ff",
				"\teor b",
				"\tsta result",
			},
		},
		{
			name: "constant folding: 255 XOR 170 -> byte",
			line: "XOR 255 WITH 170 GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda #$55",
				"\tsta result",
			},
		},
		{
			name: "constant folding: $FFFF XOR $AAAA -> word",
			line: "XOR $FFFF WITH $AAAA GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda #$55",
				"\tsta result",
				"\tlda #$55",
				"\tsta result+1",
			},
		},
		{
			name: "arrow syntax",
			line: "XOR a WITH b -> result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda a",
				"\teor b",
				"\tsta result",
			},
		},
		{
			name: "word XOR byte -> byte",
			line: "XOR wval WITH bval GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("wval", "", compiler.KindWord, 0x1234)
				st.AddVar("bval", "", compiler.KindByte, 0xFF)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda wval",
				"\teor bval",
				"\tsta result",
			},
		},
		{
			name: "word XOR byte -> word",
			line: "XOR wval WITH bval GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("wval", "", compiler.KindWord, 0x1234)
				st.AddVar("bval", "", compiler.KindByte, 0xFF)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda wval",
				"\teor bval",
				"\tsta result",
				"\tlda wval+1",
				"\tsta result+1",
			},
		},
		{
			name: "error: unknown destination variable",
			line: "XOR a WITH b GIVING unknown",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
			},
			wantErr: true,
		},
		{
			name: "error: wrong separator",
			line: "XOR a TO b GIVING result",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantErr: true,
		},
		{
			name: "error: cannot assign to constant",
			line: "XOR a WITH b GIVING MAXVAL",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
				st.AddConst("MAXVAL", "", compiler.KindByte, 255)
			},
			wantErr: true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			ctx := compiler.NewCompilerContext(&preproc.Pragma{})
			tt.setupVars(ctx.SymbolTable)

			cmd := &XorCommand{}
			line := preproc.Line{Text: tt.line, Kind: preproc.Source}

			err := cmd.Interpret(line, ctx)
			if tt.wantErr {
				if err == nil {
					t.Error("expected error, got nil")
				}
				return
			}
			if err != nil {
				t.Fatalf("Interpret() error = %v", err)
			}

			asm, err := cmd.Generate(ctx)
			if err != nil {
				t.Fatalf("Generate() error = %v", err)
			}

			if !equalAsmXor(asm, tt.wantAsm) {
				t.Errorf("Generate() mismatch\ngot:\n%s\nwant:\n%s",
					strings.Join(asm, "\n"),
					strings.Join(tt.wantAsm, "\n"))
			}
		})
	}
}

func TestXorCommand_NewSyntax(t *testing.T) {
	tests := []struct {
		name      string
		line      string
		setupVars func(*compiler.SymbolTable)
		wantAsm   []string
		wantErr   bool
	}{
		{
			name: "byte ^ byte -> byte",
			line: "result = a ^ b",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0xFF)
				st.AddVar("b", "", compiler.KindByte, 0xAA)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda a",
				"\teor b",
				"\tsta result",
			},
		},
		{
			name: "byte ^ byte -> word",
			line: "result = a ^ b",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0xFF)
				st.AddVar("b", "", compiler.KindByte, 0xAA)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda a",
				"\teor b",
				"\tsta result",
				"\tlda #0",
				"\tsta result+1",
			},
		},
		{
			name: "word ^ word -> word",
			line: "result = x ^ y",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("x", "", compiler.KindWord, 0x1234)
				st.AddVar("y", "", compiler.KindWord, 0x5678)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda x",
				"\teor y",
				"\tsta result",
				"\tlda x+1",
				"\teor y+1",
				"\tsta result+1",
			},
		},
		{
			name: "byte ^ byte_const -> word (optimization: skip eor #0)",
			line: "result = b ^ 5",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("b", "", compiler.KindByte, 0xFF)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda b",
				"\teor #$05",
				"\tsta result",
				"\tlda #0",
				"\tsta result+1",
			},
		},
		{
			name: "byte ^ word -> word (swapped to word ^ byte)",
			line: "result = bval ^ wval",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("bval", "", compiler.KindByte, 0xFF)
				st.AddVar("wval", "", compiler.KindWord, 0x1234)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda wval",
				"\teor bval",
				"\tsta result",
				"\tlda wval+1",
				"\tsta result+1",
			},
		},
		{
			name: "byte_const ^ byte -> word (optimization: skip eor #0)",
			line: "result = 5 ^ b",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("b", "", compiler.KindByte, 0xFF)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda #$05",
				"\teor b",
				"\tsta result",
				"\tlda #$00",
				"\tsta result+1",
			},
		},
		{
			name: "byte ^ word_const -> word (no optimization)",
			line: "result = b ^ 300",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("b", "", compiler.KindByte, 0xFF)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda b",
				"\teor #$2c",
				"\tsta result",
				"\tlda #0",
				"\teor #$01",
				"\tsta result+1",
			},
		},
		{
			name: "word_const ^ byte -> word (optimization: skip eor #0)",
			line: "result = 300 ^ b",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("b", "", compiler.KindByte, 0xFF)
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda #$2c",
				"\teor b",
				"\tsta result",
				"\tlda #$01",
				"\tsta result+1",
			},
		},
		{
			name: "self-assignment: word ^= byte (optimization: skip high byte entirely)",
			line: "wval = wval ^ bval",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("wval", "", compiler.KindWord, 0x1234)
				st.AddVar("bval", "", compiler.KindByte, 0xFF)
			},
			wantAsm: []string{
				"\tlda wval",
				"\teor bval",
				"\tsta wval",
			},
		},
		{
			name: "self-assignment reversed: word ^= byte (optimization via swap)",
			line: "wval = bval ^ wval",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("wval", "", compiler.KindWord, 0x1234)
				st.AddVar("bval", "", compiler.KindByte, 0xFF)
			},
			wantAsm: []string{
				"\tlda wval",
				"\teor bval",
				"\tsta wval",
			},
		},
		{
			name: "self-assignment: word ^= byte_const (optimization: skip high byte entirely)",
			line: "wval = wval ^ 42",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("wval", "", compiler.KindWord, 0x1234)
			},
			wantAsm: []string{
				"\tlda wval",
				"\teor #$2a",
				"\tsta wval",
			},
		},
		{
			name: "self-assignment: word ^= word_const (no optimization: high byte needed)",
			line: "wval = wval ^ 300",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("wval", "", compiler.KindWord, 0x1234)
			},
			wantAsm: []string{
				"\tlda wval",
				"\teor #$2c",
				"\tsta wval",
				"\tlda wval+1",
				"\teor #$01",
				"\tsta wval+1",
			},
		},
		{
			name: "self-assignment: word ^= word (no optimization: both high bytes needed)",
			line: "wval = wval ^ wval2",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("wval", "", compiler.KindWord, 0x1234)
				st.AddVar("wval2", "", compiler.KindWord, 0x5678)
			},
			wantAsm: []string{
				"\tlda wval",
				"\teor wval2",
				"\tsta wval",
				"\tlda wval+1",
				"\teor wval2+1",
				"\tsta wval+1",
			},
		},
		{
			name: "variable ^ literal",
			line: "result = a ^ $AA",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0xFF)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda a",
				"\teor #$aa",
				"\tsta result",
			},
		},
		{
			name: "constant folding",
			line: "result = 255 ^ 170",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda #$55",
				"\tsta result",
			},
		},
		{
			name: "constant folding word",
			line: "result = $FFFF ^ $AAAA",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("result", "", compiler.KindWord, 0)
			},
			wantAsm: []string{
				"\tlda #$55",
				"\tsta result",
				"\tlda #$55",
				"\tsta result+1",
			},
		},
		{
			name: "using constant in expression",
			line: "result = a ^ MASK",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0xFF)
				st.AddConst("MASK", "", compiler.KindByte, 0xAA)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"\tlda a",
				"\teor #$aa",
				"\tsta result",
			},
		},
		{
			name: "error: unknown destination",
			line: "unknown = a ^ b",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
			},
			wantErr: true,
		},
		{
			name: "error: wrong operator",
			line: "result = a + b",
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
				st.AddVar("result", "", compiler.KindByte, 0)
			},
			wantErr: true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			ctx := compiler.NewCompilerContext(&preproc.Pragma{})
			tt.setupVars(ctx.SymbolTable)

			cmd := &XorCommand{}
			line := preproc.Line{Text: tt.line, Kind: preproc.Source}

			err := cmd.Interpret(line, ctx)
			if tt.wantErr {
				if err == nil {
					t.Error("expected error, got nil")
				}
				return
			}
			if err != nil {
				t.Fatalf("Interpret() error = %v", err)
			}

			asm, err := cmd.Generate(ctx)
			if err != nil {
				t.Fatalf("Generate() error = %v", err)
			}

			if !equalAsmXor(asm, tt.wantAsm) {
				t.Errorf("Generate() mismatch\ngot:\n%s\nwant:\n%s",
					strings.Join(asm, "\n"),
					strings.Join(tt.wantAsm, "\n"))
			}
		})
	}
}

// equalAsmXor compares two assembly slices for equality
func equalAsmXor(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}