package compiler

import (
	"strings"
	"testing"

	"c65gm/internal/preproc"
)

// Helper to create a test Line
func makeLine(text string) preproc.Line {
	return preproc.Line{
		RawText:        text,
		Text:           text,
		Filename:       "test.c65",
		LineNo:         1,
		Kind:           preproc.Source,
		PragmaSetIndex: 0,
	}
}

func TestFixIntuitiveFuncs(t *testing.T) {
	tests := []struct {
		input    string
		expected string
	}{
		{"func(a,b)", "func ( a b )"},
		{"func( a, b )", "func ( a b )"},
		{"func(a,b,c)", "func ( a b c )"},
		{"CALL func()", "CALL func ( )"},
		{"func()", "func ( )"},
		{`func("hello",x)`, `func ( "hello" x )`},
		{`func("a,b",c)`, `func ( "a,b" c )`},
		{"func  (  a  ,  b  )", "func ( a b )"},
	}

	for _, tt := range tests {
		result := fixIntuitiveFuncs(tt.input)
		if result != tt.expected {
			t.Errorf("fixIntuitiveFuncs(%q) = %q, want %q", tt.input, result, tt.expected)
		}
	}
}

func TestBuildComplexParams(t *testing.T) {
	tests := []struct {
		input    []string
		expected []string
		wantErr  bool
	}{
		{
			input:    []string{"a", "b", "c"},
			expected: []string{"a", "b", "c"},
			wantErr:  false,
		},
		{
			input:    []string{"{BYTE", "x}"},
			expected: []string{"{BYTE x}"},
			wantErr:  false,
		},
		{
			input:    []string{"{WORD", "ptr}"},
			expected: []string{"{WORD ptr}"},
			wantErr:  false,
		},
		{
			input:    []string{"{BYTE", "a}", "{WORD", "b}"},
			expected: []string{"{BYTE a}", "{WORD b}"},
			wantErr:  false,
		},
		{
			input:    []string{"x", "{BYTE", "a}", "y"},
			expected: []string{"x", "{BYTE a}", "y"},
			wantErr:  false,
		},
		{
			input:    []string{"{BYTE", "x"},
			expected: nil,
			wantErr:  true, // unclosed
		},
		{
			input:    []string{"x}"},
			expected: nil,
			wantErr:  true, // unmatched close
		},
		{
			input:    []string{"{BYTE", "{WORD", "x}"},
			expected: nil,
			wantErr:  true, // nested open
		},
	}

	for _, tt := range tests {
		result, err := buildComplexParams(tt.input)
		if tt.wantErr {
			if err == nil {
				t.Errorf("buildComplexParams(%v) expected error, got nil", tt.input)
			}
			continue
		}
		if err != nil {
			t.Errorf("buildComplexParams(%v) unexpected error: %v", tt.input, err)
			continue
		}
		if len(result) != len(tt.expected) {
			t.Errorf("buildComplexParams(%v) = %v, want %v", tt.input, result, tt.expected)
			continue
		}
		for i := range result {
			if result[i] != tt.expected[i] {
				t.Errorf("buildComplexParams(%v)[%d] = %q, want %q", tt.input, i, result[i], tt.expected[i])
			}
		}
	}
}

func TestParseParams(t *testing.T) {
	tests := []struct {
		input    string
		expected []string
		wantErr  bool
	}{
		{"FUNC test", []string{"FUNC", "test"}, false},
		{"FUNC test ( a b )", []string{"FUNC", "test", "(", "a", "b", ")"}, false},
		{`CALL print ( "hello world" )`, []string{"CALL", "print", "(", `"hello world"`, ")"}, false},
		{"  FUNC   test  ", []string{"FUNC", "test"}, false},
		{`func("unterminated`, nil, true},
	}

	for _, tt := range tests {
		result, err := parseParams(tt.input)
		if tt.wantErr {
			if err == nil {
				t.Errorf("parseParams(%q) expected error, got nil", tt.input)
			}
			continue
		}
		if err != nil {
			t.Errorf("parseParams(%q) unexpected error: %v", tt.input, err)
			continue
		}
		if len(result) != len(tt.expected) {
			t.Errorf("parseParams(%q) = %v, want %v", tt.input, result, tt.expected)
			continue
		}
		for i := range result {
			if result[i] != tt.expected[i] {
				t.Errorf("parseParams(%q)[%d] = %q, want %q", tt.input, i, result[i], tt.expected[i])
			}
		}
	}
}

func TestParseParamSpec(t *testing.T) {
	tests := []struct {
		input        string
		wantDir      ParamDirection
		wantName     string
		wantImplicit bool
		wantImplDecl string
		wantErr      bool
	}{
		{"varname", DirIn, "varname", false, "", false},
		{"in:varname", DirIn, "varname", false, "", false},
		{"out:varname", DirOut, "varname", false, "", false},
		{"io:varname", DirIn | DirOut, "varname", false, "", false},
		{"{BYTE temp}", DirIn, "temp", true, "BYTE temp", false},
		{"{WORD result}", DirIn, "result", true, "WORD result", false},
		{"out:{BYTE x}", DirOut, "x", true, "BYTE x", false},
		{"io:{WORD ptr}", DirIn | DirOut, "ptr", true, "WORD ptr", false},
		{"invalid:dir:x", 0, "", false, "", true},
	}

	for _, tt := range tests {
		dir, name, isImpl, implDecl, err := parseParamSpec(tt.input)
		if tt.wantErr {
			if err == nil {
				t.Errorf("parseParamSpec(%q) expected error, got nil", tt.input)
			}
			continue
		}
		if err != nil {
			t.Errorf("parseParamSpec(%q) unexpected error: %v", tt.input, err)
			continue
		}
		if dir != tt.wantDir {
			t.Errorf("parseParamSpec(%q) direction = %v, want %v", tt.input, dir, tt.wantDir)
		}
		if name != tt.wantName {
			t.Errorf("parseParamSpec(%q) name = %q, want %q", tt.input, name, tt.wantName)
		}
		if isImpl != tt.wantImplicit {
			t.Errorf("parseParamSpec(%q) implicit = %v, want %v", tt.input, isImpl, tt.wantImplicit)
		}
		if implDecl != tt.wantImplDecl {
			t.Errorf("parseParamSpec(%q) implDecl = %q, want %q", tt.input, implDecl, tt.wantImplDecl)
		}
	}
}

func TestHandleFuncDecl_VoidFunction(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	asm, err := fh.HandleFuncDecl(makeLine("FUNC test_void"))
	if err != nil {
		t.Fatalf("HandleFuncDecl failed: %v", err)
	}

	if len(asm) != 1 {
		t.Fatalf("expected 1 asm line, got %d", len(asm))
	}
	if asm[0] != "test_void" {
		t.Errorf("expected label 'test_void', got %q", asm[0])
	}

	if !fh.FuncExists("test_void") {
		t.Error("function should exist")
	}
}

func TestHandleFuncDecl_WithExistingParams(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	// Pre-declare parameters
	st.AddVar("x", "test_func", KindByte, 0)
	st.AddVar("y", "test_func", KindWord, 0)

	asm, err := fh.HandleFuncDecl(makeLine("FUNC test_func ( x y )"))
	if err != nil {
		t.Fatalf("HandleFuncDecl failed: %v", err)
	}

	if len(asm) != 1 {
		t.Fatalf("expected 1 asm line, got %d", len(asm))
	}

	funcDecl := fh.findFunc("test_func")
	if funcDecl == nil {
		t.Fatal("function not found")
	}
	if len(funcDecl.Params) != 2 {
		t.Fatalf("expected 2 params, got %d", len(funcDecl.Params))
	}
}

func TestHandleFuncDecl_ImplicitDeclarations(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	asm, err := fh.HandleFuncDecl(makeLine("FUNC test_impl ( {BYTE a} {WORD b} )"))
	if err != nil {
		t.Fatalf("HandleFuncDecl failed: %v", err)
	}

	if len(asm) != 1 {
		t.Fatalf("expected 1 asm line, got %d", len(asm))
	}

	// Check that variables were declared
	symA := st.Lookup("a", []string{"test_impl"})
	if symA == nil {
		t.Fatal("parameter 'a' not declared")
	}
	if !symA.IsByte() {
		t.Error("parameter 'a' should be byte")
	}

	symB := st.Lookup("b", []string{"test_impl"})
	if symB == nil {
		t.Fatal("parameter 'b' not declared")
	}
	if !symB.IsWord() {
		t.Error("parameter 'b' should be word")
	}
}

func TestHandleFuncDecl_WithDirections(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	_, err := fh.HandleFuncDecl(makeLine("FUNC test_dir ( in:{BYTE a} out:{BYTE b} io:{WORD c} )"))
	if err != nil {
		t.Fatalf("HandleFuncDecl failed: %v", err)
	}

	funcDecl := fh.findFunc("test_dir")
	if funcDecl == nil {
		t.Fatal("function not found")
	}

	if len(funcDecl.Params) != 3 {
		t.Fatalf("expected 3 params, got %d", len(funcDecl.Params))
	}

	if funcDecl.Params[0].Direction != DirIn {
		t.Error("param 0 should be DirIn")
	}
	if funcDecl.Params[1].Direction != DirOut {
		t.Error("param 1 should be DirOut")
	}
	if funcDecl.Params[2].Direction != (DirIn | DirOut) {
		t.Error("param 2 should be DirIn|DirOut")
	}
}

func TestHandleFuncDecl_Errors(t *testing.T) {
	tests := []struct {
		name    string
		line    string
		preDecl func(*SymbolTable)
		wantErr string
	}{
		{
			name:    "redeclaration",
			line:    "FUNC duplicate ( {BYTE x} )",
			preDecl: func(st *SymbolTable) {},
			wantErr: "already declared",
		},
		{
			name:    "missing param",
			line:    "FUNC test ( missing )",
			wantErr: "not declared",
		},
		{
			name: "const param",
			line: "FUNC test ( constval )",
			preDecl: func(st *SymbolTable) {
				st.AddConst("constval", "test", KindByte, 42)
			},
			wantErr: "cannot be a constant",
		},
		{
			name:    "invalid implicit",
			line:    "FUNC test ( {INVALID x} )",
			wantErr: "must be BYTE or WORD",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			st := NewSymbolTable()
			ls := NewLabelStack("L")
			csh := NewConstantStringHandler()
			pragma := preproc.NewPragma()
			fh := NewFunctionHandler(st, ls, csh, pragma)

			if tt.preDecl != nil {
				tt.preDecl(st)
			}

			// Special case for redeclaration test
			if tt.name == "redeclaration" {
				fh.HandleFuncDecl(makeLine("FUNC duplicate ( {BYTE x} )"))
			}

			_, err := fh.HandleFuncDecl(makeLine(tt.line))
			if err == nil {
				t.Fatal("expected error, got nil")
			}
			if !strings.Contains(err.Error(), tt.wantErr) {
				t.Errorf("error %q does not contain %q", err.Error(), tt.wantErr)
			}
		})
	}
}

func TestHandleFuncCall_VarArgs(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	// Declare function with params
	st.AddVar("param_a", "test_func", KindByte, 0)
	st.AddVar("param_b", "test_func", KindWord, 0)
	fh.HandleFuncDecl(makeLine("FUNC test_func ( param_a param_b )"))

	// Declare caller variables
	st.AddVar("var_a", "", KindByte, 0)
	st.AddVar("var_b", "", KindWord, 0)

	asm, err := fh.HandleFuncCall(makeLine("CALL test_func ( var_a var_b )"))
	if err != nil {
		t.Fatalf("HandleFuncCall failed: %v", err)
	}

	// Check generated assembly
	expectedLines := []string{
		"  lda var_a",
		"  sta test_func_param_a",
		"  lda var_b",
		"  sta test_func_param_b",
		"  lda var_b+1",
		"  sta test_func_param_b+1",
		"  jsr test_func",
	}

	if len(asm) != len(expectedLines) {
		t.Fatalf("expected %d asm lines, got %d", len(expectedLines), len(asm))
	}

	for i, expected := range expectedLines {
		if asm[i] != expected {
			t.Errorf("asm[%d] = %q, want %q", i, asm[i], expected)
		}
	}
}

func TestHandleFuncCall_OutParams(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	// Declare function with out param
	st.AddVar("result", "get_result", KindByte, 0)
	fh.HandleFuncDecl(makeLine("FUNC get_result ( out:result )"))

	// Declare caller variable
	st.AddVar("output", "", KindByte, 0)

	asm, err := fh.HandleFuncCall(makeLine("CALL get_result ( output )"))
	if err != nil {
		t.Fatalf("HandleFuncCall failed: %v", err)
	}

	// Should have JSR and OUT assignment
	found_jsr := false
	found_out := false
	for _, line := range asm {
		if strings.Contains(line, "jsr get_result") {
			found_jsr = true
		}
		if strings.Contains(line, "lda get_result_result") {
			found_out = true
		}
	}

	if !found_jsr {
		t.Error("missing jsr instruction")
	}
	if !found_out {
		t.Error("missing out assignment")
	}
}

func TestHandleFuncCall_ConstArgs(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	// Declare function
	st.AddVar("x", "test_const", KindByte, 0)
	st.AddVar("y", "test_const", KindWord, 0)
	fh.HandleFuncDecl(makeLine("FUNC test_const ( x y )"))

	asm, err := fh.HandleFuncCall(makeLine("CALL test_const ( 42 $1234 )"))
	if err != nil {
		t.Fatalf("HandleFuncCall failed: %v", err)
	}

	// Check for immediate loads
	foundByte := false
	foundWord := false
	for _, line := range asm {
		if strings.Contains(line, "lda #42") {
			foundByte = true
		}
		if strings.Contains(line, "lda #18") { // 0x12
			foundWord = true
		}
	}

	if !foundByte {
		t.Error("missing byte constant load")
	}
	if !foundWord {
		t.Error("missing word constant load")
	}
}

func TestHandleFuncCall_LabelArg(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	// Declare function
	st.AddVar("ptr", "test_label", KindWord, 0)
	fh.HandleFuncDecl(makeLine("FUNC test_label ( ptr )"))

	asm, err := fh.HandleFuncCall(makeLine("CALL test_label ( @my_label )"))
	if err != nil {
		t.Fatalf("HandleFuncCall failed: %v", err)
	}

	// Check for label reference
	foundLow := false
	foundHigh := false
	for _, line := range asm {
		if strings.Contains(line, "#<my_label") {
			foundLow = true
		}
		if strings.Contains(line, "#>my_label") {
			foundHigh = true
		}
	}

	if !foundLow || !foundHigh {
		t.Error("missing label reference code")
	}
}

func TestHandleFuncCall_StringArg(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	// Declare function
	st.AddVar("str_ptr", "print", KindWord, 0)
	fh.HandleFuncDecl(makeLine("FUNC print ( str_ptr )"))

	asm, err := fh.HandleFuncCall(makeLine(`CALL print ( "hello" )`))
	if err != nil {
		t.Fatalf("HandleFuncCall failed: %v", err)
	}

	// Check that label was generated
	if ls.Size() != 1 {
		t.Errorf("expected 1 label generated, got %d", ls.Size())
	}

	// Check for label reference in asm
	foundLabel := false
	for _, line := range asm {
		if strings.Contains(line, "#<L1") || strings.Contains(line, "#>L1") {
			foundLabel = true
			break
		}
	}

	if !foundLabel {
		t.Error("missing string label reference")
	}
}

func TestHandleFuncCall_Errors(t *testing.T) {
	tests := []struct {
		name    string
		setup   func(*FunctionHandler, *SymbolTable)
		line    string
		wantErr string
	}{
		{
			name:    "function not declared",
			setup:   func(fh *FunctionHandler, st *SymbolTable) {},
			line:    "CALL undefined ( )",
			wantErr: "not declared",
		},
		{
			name: "wrong arg count",
			setup: func(fh *FunctionHandler, st *SymbolTable) {
				st.AddVar("x", "test", KindByte, 0)
				fh.HandleFuncDecl(makeLine("FUNC test ( x )"))
			},
			line:    "CALL test ( 1 2 )",
			wantErr: "expected 1 arguments, got 2",
		},
		{
			name: "type mismatch",
			setup: func(fh *FunctionHandler, st *SymbolTable) {
				st.AddVar("param", "test", KindByte, 0)
				fh.HandleFuncDecl(makeLine("FUNC test ( param )"))
				st.AddVar("wvar", "", KindWord, 0)
			},
			line:    "CALL test ( wvar )",
			wantErr: "type mismatch",
		},
		{
			name: "const to out param",
			setup: func(fh *FunctionHandler, st *SymbolTable) {
				st.AddVar("result", "test", KindByte, 0)
				fh.HandleFuncDecl(makeLine("FUNC test ( out:result )"))
			},
			line:    "CALL test ( 42 )",
			wantErr: "out/io parameter",
		},
		{
			name: "label to byte param",
			setup: func(fh *FunctionHandler, st *SymbolTable) {
				st.AddVar("x", "test", KindByte, 0)
				fh.HandleFuncDecl(makeLine("FUNC test ( x )"))
			},
			line:    "CALL test ( @label )",
			wantErr: "byte parameter",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			st := NewSymbolTable()
			ls := NewLabelStack("L")
			csh := NewConstantStringHandler()
			pragma := preproc.NewPragma()
			fh := NewFunctionHandler(st, ls, csh, pragma)

			tt.setup(fh, st)

			_, err := fh.HandleFuncCall(makeLine(tt.line))
			if err == nil {
				t.Fatal("expected error, got nil")
			}
			if !strings.Contains(err.Error(), tt.wantErr) {
				t.Errorf("error %q does not contain %q", err.Error(), tt.wantErr)
			}
		})
	}
}

func TestEndFunction(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	// Declare function (pushes to stack)
	fh.HandleFuncDecl(makeLine("FUNC test ( {BYTE x} )"))

	if fh.CurrentFunction() != "test" {
		t.Errorf("current function = %q, want 'test'", fh.CurrentFunction())
	}

	// End function
	fh.EndFunction()

	if fh.CurrentFunction() != "" {
		t.Errorf("current function = %q, want ''", fh.CurrentFunction())
	}
}

func TestCurrentFunction(t *testing.T) {
	st := NewSymbolTable()
	ls := NewLabelStack("L")
	csh := NewConstantStringHandler()
	pragma := preproc.NewPragma()
	fh := NewFunctionHandler(st, ls, csh, pragma)

	if fh.CurrentFunction() != "" {
		t.Error("expected empty current function initially")
	}

	fh.HandleFuncDecl(makeLine("FUNC func1 ( {BYTE x} )"))
	if fh.CurrentFunction() != "func1" {
		t.Errorf("expected 'func1', got %q", fh.CurrentFunction())
	}

	fh.HandleFuncDecl(makeLine("FUNC func2 ( {BYTE y} )"))
	if fh.CurrentFunction() != "func2" {
		t.Errorf("expected 'func2', got %q", fh.CurrentFunction())
	}

	fh.EndFunction()
	if fh.CurrentFunction() != "" {
		t.Errorf("expected '', got %q", fh.CurrentFunction())
	}
}