package commands

import (
	"fmt"
	"strings"
	"testing"

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

func TestElseCommand_WillHandle(t *testing.T) {
	cmd := &ElseCommand{}

	tests := []struct {
		name string
		line string
		want bool
	}{
		{"ELSE", "ELSE", true},
		{"not ELSE", "IF a = b", false},
		{"empty", "", 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 TestEndIfCommand_WillHandle(t *testing.T) {
	cmd := &EndIfCommand{}

	tests := []struct {
		name string
		line string
		want bool
	}{
		{"ENDIF", "ENDIF", true},
		{"not ENDIF", "IF a = b", false},
		{"empty", "", 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 TestIfElseEndif_Integration(t *testing.T) {
	tests := []struct {
		name      string
		lines     []string
		setupVars func(*compiler.SymbolTable)
		wantAsm   []string
	}{
		{
			name: "IF...ENDIF (no ELSE)",
			lines: []string{
				"IF a = b",
				"ENDIF",
			},
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"; IF a = b",
				"\tlda a",
				"\tcmp b",
				"\tbne _I1",
				"; ENDIF",
				"_I1",
			},
		},
		{
			name: "IF...ELSE...ENDIF",
			lines: []string{
				"IF a = b",
				"ELSE",
				"ENDIF",
			},
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"; IF a = b",
				"\tlda a",
				"\tcmp b",
				"\tbne _I1",
				"; ELSE",
				"\tjmp _I2",
				"_I1",
				"; ENDIF",
				"_I2",
			},
		},
		{
			name: "nested IF statements",
			lines: []string{
				"IF a = 10",
				"IF b = 20",
				"ENDIF",
				"ENDIF",
			},
			setupVars: func(st *compiler.SymbolTable) {
				st.AddVar("a", "", compiler.KindByte, 0)
				st.AddVar("b", "", compiler.KindByte, 0)
			},
			wantAsm: []string{
				"; IF a = 10",
				"\tlda a",
				"\tcmp #$0a",
				"\tbne _I1",
				"; IF b = 20",
				"\tlda b",
				"\tcmp #$14",
				"\tbne _I2",
				"; ENDIF",
				"_I2",
				"; ENDIF",
				"_I1",
			},
		},
	}

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

			var allAsm []string

			for _, lineText := range tt.lines {
				line := preproc.Line{Text: lineText, Kind: preproc.Source, PragmaSetIndex: 0}

				// Determine which command to use
				var cmd compiler.Command
				if strings.HasPrefix(strings.ToUpper(lineText), "IF") {
					cmd = &IfCommand{}
				} else if strings.ToUpper(lineText) == "ELSE" {
					cmd = &ElseCommand{}
				} else if strings.ToUpper(lineText) == "ENDIF" {
					cmd = &EndIfCommand{}
				} else {
					t.Fatalf("unknown command: %s", lineText)
				}

				err := cmd.Interpret(line, ctx)
				if err != nil {
					t.Fatalf("Interpret(%q) error = %v", lineText, err)
				}

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

				allAsm = append(allAsm, fmt.Sprintf("; %s", lineText))
				allAsm = append(allAsm, asm...)
			}

			if !equalAsmElse(allAsm, tt.wantAsm) {
				t.Errorf("Assembly mismatch\ngot:\n%s\nwant:\n%s",
					strings.Join(allAsm, "\n"),
					strings.Join(tt.wantAsm, "\n"))
			}
		})
	}
}

func TestElseCommand_Errors(t *testing.T) {
	tests := []struct {
		name    string
		line    string
		wantErr string
	}{
		{
			name:    "ELSE without IF",
			line:    "ELSE",
			wantErr: "stack underflow",
		},
		{
			name:    "wrong param count",
			line:    "ELSE extra",
			wantErr: "wrong number of parameters",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			ctx := compiler.NewCompilerContext(preproc.NewPragma())
			cmd := &ElseCommand{}
			line := preproc.Line{Text: tt.line, Kind: preproc.Source}

			err := cmd.Interpret(line, ctx)
			if err == nil {
				t.Fatal("expected error, got nil")
			}
			if !strings.Contains(err.Error(), tt.wantErr) {
				t.Errorf("error = %q, want substring %q", err.Error(), tt.wantErr)
			}
		})
	}
}

func TestEndIfCommand_Errors(t *testing.T) {
	tests := []struct {
		name    string
		line    string
		wantErr string
	}{
		{
			name:    "ENDIF without IF",
			line:    "ENDIF",
			wantErr: "stack underflow",
		},
		{
			name:    "wrong param count",
			line:    "ENDIF extra",
			wantErr: "wrong number of parameters",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			ctx := compiler.NewCompilerContext(preproc.NewPragma())
			cmd := &EndIfCommand{}
			line := preproc.Line{Text: tt.line, Kind: preproc.Source}

			err := cmd.Interpret(line, ctx)
			if err == nil {
				t.Fatal("expected error, got nil")
			}
			if !strings.Contains(err.Error(), tt.wantErr) {
				t.Errorf("error = %q, want substring %q", err.Error(), tt.wantErr)
			}
		})
	}
}

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