package parser

import (
	"testing"

	"gointerpreter/ast"
	"gointerpreter/lexer"
)

func Test_LetStatement(t *testing.T) {
	input := `
    let x = 5;
    let y = 10;
    let foobar = 324453;
    `

	l := lexer.New(input)
	p := New(l)

	program := p.ParseProgram()
	checkParserErrors(t, p)

	if program == nil {
		t.Fatalf("ParseProgram() returned nil")
	}

	if len(program.Statements) != 3 {
		t.Fatalf("program.Statement does not contained 3 statements, got [%d]", len(program.Statements))
	}

	tests := []struct {
		expectedIdentifier string
	}{
		{"x"},
		{"y"},
		{"foobar"},
	}

	for i, tt := range tests {
		statement := program.Statements[i]

		if !testLetStatement(t, statement, tt.expectedIdentifier) {
			return
		}
	}
}

func testLetStatement(t *testing.T, s ast.Statement, name string) bool {
	if s.TokenLiteral() != "let" {
		t.Errorf("s.TokenLiteral() is not [let], got [%s]", s.TokenLiteral())
		return false
	}

	letStatement, ok := s.(*ast.LetStatement)
	if !ok {
		t.Errorf("s is not a *ast.LetStatement, got [%T]", s)
		return false
	}

	if letStatement.Name.Value != name {
		t.Errorf("letStatement.Name.Value is not [%s], got [%s]", name, letStatement.Name.Value)
		return false
	}

	if letStatement.Name.TokenLiteral() != name {
		t.Errorf("letStatement.TokenLiteral() is not [%s], got [%s]", name, letStatement.TokenLiteral())
		return false
	}

	return true
}

func checkParserErrors(t *testing.T, p *Parser) {
	errors := p.Errors()

	if len(errors) == 0 {
		return
	}

	t.Errorf("parser has [%d] errors", len(errors))
	for _, e := range errors {
		t.Errorf("parser error: %q", e)
	}

	t.FailNow()
}

func Test_ReturnStatement(t *testing.T) {
	input := `
    return 5;
    return 10;
    return 234342;
    `

	l := lexer.New(input)
	p := New(l)

	program := p.ParseProgram()
	checkParserErrors(t, p)

	if program == nil {
		t.Fatalf("ParseProgram() returned nil")
	}

	if len(program.Statements) != 3 {
		t.Fatalf("program.Statement does not contained 3 statements, got [%d]", len(program.Statements))
	}

	for _, stmt := range program.Statements {
		returnStmt, ok := stmt.(*ast.ReturnStatement)
		if !ok {
			t.Errorf("stmt is not *ast.ReturnStatement, got [%T]", stmt)
			continue
		}

		if returnStmt.TokenLiteral() != "return" {
			t.Errorf("returnStmt.TokenLiteral() is not [return], got [%q]", returnStmt.TokenLiteral())
		}
	}
}