package main

import (
	"errors"
	"os"
	"path/filepath"
	"slices"
	"testing"
)

func TestNewMigrationReturnsMigrationWithProperties(t *testing.T) {
	migration := NewMigration("path", "name", "requires")

	if migration.Path != "path" || migration.Name != "name" || migration.Requires != "requires" || migration.Run != false {
		t.Errorf("Expected Migration with passed values and default, got %#v", migration)
	}

}

func TestMigrationBytesReturnsBytesFromMigrationFile(t *testing.T) {
	mockMigrationData := []byte("SELECT * FROM myTable;")

	migrationRoot := t.TempDir()
	migrationPath := filepath.Join(migrationRoot, "0001.sql")
	os.WriteFile(migrationPath, mockMigrationData, 0750)

	migration := NewMigration(migrationPath, "TestMigration", "")

	migrationBytes, _ := migration.Bytes()
	if !slices.Equal(migrationBytes, mockMigrationData) {
		t.Errorf("Expected bytes to be %#v, got %#v.", mockMigrationData, migrationBytes)
	}
}

func TestMigrationBytesErrorsIfFileCannotBeRead(t *testing.T) {
	migration := NewMigration("not-a-file", "TestMigration", "")

	_, err := migration.Bytes()

	if err == nil {
		t.Errorf("Expected error, got nil.")
	}
}

func TestMigrationTextReturnsFileContentAsString(t *testing.T) {
	mockMigrationData := []byte("SELECT * FROM myTable;")

	migrationRoot := t.TempDir()
	migrationPath := filepath.Join(migrationRoot, "0001.sql")
	os.WriteFile(migrationPath, mockMigrationData, 0750)

	migration := NewMigration(migrationPath, "TestMigration", "")

	migrationStr, _ := migration.Text()

	if migrationStr != string(mockMigrationData) {
		t.Errorf("Expected text to be %#v, got %#v.", string(mockMigrationData), migrationStr)
	}
}

func TestMigrationTextErrorsIfFileCannotBeRead(t *testing.T) {
	migration := NewMigration("not-a-file", "TestMigration", "")

	_, err := migration.Text()

	if err == nil {
		t.Errorf("Expected error, got nil.")
	}
}

func TestMigrationSqlReturnsSqlAsStringWithoutComments(t *testing.T) {
	mockMigrationData := []byte("SELECT * FROM myTable;")
	mockMigrationComment := []byte("--comment\n")
	mockMigrationDataWithComment := append(mockMigrationComment, mockMigrationData...)

	migrationRoot := t.TempDir()
	migrationPath := filepath.Join(migrationRoot, "0001.sql")
	os.WriteFile(migrationPath, mockMigrationDataWithComment, 0750)

	migration := NewMigration(migrationPath, "TestMigration", "")

	migrationStr, _ := migration.Sql()

	if migrationStr != string(mockMigrationData) {
		t.Errorf("Expected text to be %#v, got %#v.", string(mockMigrationData), migrationStr)
	}
}

func TestMigrationSqlErrorsIfFileCannotBeRead(t *testing.T) {
	migration := NewMigration("not-a-file", "TestMigration", "")

	_, err := migration.Sql()

	if err == nil {
		t.Errorf("Expected error, got nil.")
	}
}

func TestMigrationApplyRunsTheSqlOnTheGivenDatabase(t *testing.T) {
	mockMigrationData := []byte("SELECT * FROM myTable;")

	migrationRoot := t.TempDir()
	migrationPath := filepath.Join(migrationRoot, "0001.sql")
	os.WriteFile(migrationPath, mockMigrationData, 0750)

	migration := NewMigration(migrationPath, "TestMigration", "")

	mockDB := &MockSqlDB{}

	err := migration.Apply(mockDB)

	if err != nil {
		t.Errorf("Did not expect error, got %#v", err)
	}

	expectedQueries := []string{string(mockMigrationData)}
	if !slices.Equal(mockDB.queries, expectedQueries) {
		t.Errorf("Expected queries %#v, got %#v", expectedQueries, mockDB.queries)
	}
}

func TestMigrationApplyErrorsIfFileCannotBeRead(t *testing.T) {
	migration := NewMigration("not-a-file", "TestMigration", "")

	mockDB := &MockSqlDB{}

	err := migration.Apply(mockDB)

	if err == nil {
		t.Errorf("Expected error, got nil.")
	}
}

func TestMigrationApplyErrorsIfRunningSqlFails(t *testing.T) {
	mockMigrationData := []byte("SELECT * FROM myTable;")

	migrationRoot := t.TempDir()
	migrationPath := filepath.Join(migrationRoot, "0001.sql")
	os.WriteFile(migrationPath, mockMigrationData, 0750)

	migration := NewMigration(migrationPath, "TestMigration", "")

	mockDB := &MockSqlDB{
		mockedError: errors.New("test error"),
	}

	err := migration.Apply(mockDB)

	if err == nil {
		t.Errorf("Expected error, got nil")
	}
}