package store_test

import (
	"context"
	"database/sql"
	"errors"
	"path/filepath"
	"strings"
	"testing"

	"github.com/pressly/goose/v3"

	"git.avsdev.uk/Go/job-search/internal/store"
)

// Run with: go test -tags sqlite_fts5 ./...

func tempDBPath(t *testing.T) string {
	t.Helper()
	return filepath.Join(t.TempDir(), "migrate.db")
}

func newMigrator(t *testing.T) (*goose.Provider, *sql.DB) {
	t.Helper()
	db, err := store.OpenDB(filepath.Join(t.TempDir(), "migrate.db"))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() {
		db.Close()
	})

	m, err := store.NewMigrator(db)
	if err != nil {
		t.Fatal(err)
	}

	return m, db
}

func version(t *testing.T, m *goose.Provider) int64 {
	t.Helper()
	v, err := m.GetDBVersion(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	return v
}

func TestOpenRequiresMigration(t *testing.T) {
	ctx := context.Background()
	path := tempDBPath(t)

	if _, err := store.Open(ctx, path); !errors.Is(err, store.ErrNeedsMigration) {
		t.Fatalf("fresh database: err = %v, want ErrNeedsMigration", err)
	}

	db, err := store.OpenDB(path)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()
	m, err := store.NewMigrator(db)
	if err != nil {
		t.Fatal(err)
	}

	if _, err := m.UpByOne(ctx); err != nil {
		t.Fatal(err)
	}
	if _, err := store.Open(ctx, path); !errors.Is(err, store.ErrNeedsMigration) {
		t.Fatalf("partly migrated: err = %v, want ErrNeedsMigration", err)
	}

	if _, err := m.Up(ctx); err != nil {
		t.Fatal(err)
	}
	s, err := store.Open(ctx, path)
	if err != nil {
		t.Fatalf("fully migrated: %v", err)
	}
	s.Close()
}

func TestOpenRejectsNewerSchema(t *testing.T) {
	ctx := context.Background()
	path := tempDBPath(t)
	s, err := store.Open(ctx, path, store.WithAutoMigrate())
	if err != nil {
		t.Fatal(err)
	}
	s.Close()

	// Simulate a migration applied by a newer build.
	db, err := store.OpenDB(path)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()
	if _, err := db.Exec(
		`INSERT INTO goose_db_version (version_id, is_applied) VALUES (9999, 1)`,
	); err != nil {
		t.Fatal(err)
	}

	for name, opts := range map[string][]store.Option{
		"check":        nil,
		"auto-migrate": {store.WithAutoMigrate()},
	} {
		_, err := store.Open(ctx, path, opts...)
		if !errors.Is(err, store.ErrSchemaTooNew) {
			t.Errorf("%s: err = %v, want ErrSchemaTooNew", name, err)
		}
	}
}

func TestMigrateDownAllAndUpAgain(t *testing.T) {
	ctx := context.Background()
	path := tempDBPath(t)
	db, err := store.OpenDB(path)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Close()
	m, err := store.NewMigrator(db)
	if err != nil {
		t.Fatal(err)
	}

	if _, err := m.Up(ctx); err != nil {
		t.Fatal(err)
	}
	if v, _ := m.GetDBVersion(ctx); v != store.LatestVersion(m) {
		t.Fatalf("after up: version %d, want %d", v, store.LatestVersion(m))
	}

	if _, err := m.DownTo(ctx, 0); err != nil {
		t.Fatalf("down to 0: %v", err)
	}
	var tables int
	query := `
		SELECT count(*) FROM sqlite_master
		WHERE type IN ('table', 'index', 'trigger')
			AND name NOT LIKE 'sqlite_%'
			AND name != 'goose_db_version'`
	if err := db.QueryRow(query).Scan(&tables); err != nil {
		t.Fatal(err)
	}
	if tables != 0 {
		t.Errorf("after down to 0: %d schema objects remain", tables)
	}

	if _, err := m.Up(ctx); err != nil {
		t.Fatalf("up again: %v", err)
	}
	s, err := store.Open(ctx, path)
	if err != nil {
		t.Fatalf("open after round trip: %v", err)
	}
	s.Close()
}

func TestUpAllThenUpToDate(t *testing.T) {
	ctx := context.Background()
	m, _ := newMigrator(t)
	latest := store.LatestVersion(m)

	results, err := store.StepUp(ctx, m, 0)
	if err != nil {
		t.Fatal(err)
	}
	if got := len(results); got != int(latest) {
		t.Fatalf("applied %d migrations, want %d.", got, latest)
	}

	results, err = store.StepUp(ctx, m, 0)
	if err != nil {
		t.Fatal(err)
	}

	if len(results) != 0 {
		t.Fatalf("expected no further migrations, got %d.", len(results))
	}
}

func TestUpBySteps(t *testing.T) {
	ctx := context.Background()
	m, _ := newMigrator(t)

	nToApply := 2

	_, err := store.StepUp(ctx, m, nToApply)
	if err != nil {
		t.Fatal(err)
	}
	if v := version(t, m); v != int64(nToApply) {
		t.Fatalf("after 2 steps: version %d", v)
	}
	// More steps than pending stops at the latest version.
	_, err = store.StepUp(ctx, m, 50)
	if err != nil {
		t.Fatal(err)
	}
	if v := version(t, m); v != store.LatestVersion(m) {
		t.Fatalf("after 50 steps: version %d", v)
	}
}

func TestDownBySteps(t *testing.T) {
	ctx := context.Background()
	m, _ := newMigrator(t)

	_, err := store.StepUp(ctx, m, 0)
	if err != nil {
		t.Fatal(err)
	}

	_, err = store.StepDown(ctx, m, 2, false)
	if err != nil {
		t.Fatal(err)
	}
	if v, want := version(t, m), store.LatestVersion(m)-2; v != want {
		t.Fatalf("after 2 down steps: version %d, want %d", v, want)
	}
}

func TestDownAllRequiresConfirmation(t *testing.T) {
	ctx := context.Background()
	m, _ := newMigrator(t)

	_, err := store.StepUp(ctx, m, 0)
	if err != nil {
		t.Fatal(err)
	}

	hasErrored := false
	for name, steps := range map[string]int{
		"steps 0":                 0,
		"more steps than applied": 99,
	} {
		_, err := store.StepDown(ctx, m, steps, false)
		if !errors.Is(err, store.ErrWouldEmptyDatabase) {
			t.Errorf("%s: %s", name, err)
			hasErrored = true
		}
		if v := version(t, m); v != store.LatestVersion(m) {
			t.Errorf("%s: version changed to %d", name, v)
			hasErrored = true
		}
	}
	if hasErrored {
		t.FailNow()
	}

	_, err = store.StepDown(ctx, m, 0, true)
	if err != nil {
		t.Fatal(err)
	}
	if v := version(t, m); v != 0 {
		t.Fatalf("after confirmed down: version %d", v)
	}
}

func TestDownOnEmptyDatabase(t *testing.T) {
	m, _ := newMigrator(t)
	results, err := store.StepDown(context.Background(), m, 0, false)
	if err != nil {
		t.Fatal(err)
	}
	if len(results) != 0 {
		t.Fatalf("expected no further migrations, got %d.", len(results))
	}
}

func TestNewerDatabaseIsRefused(t *testing.T) {
	ctx := context.Background()
	m, db := newMigrator(t)

	if _, err := store.StepUp(ctx, m, 0); err != nil {
		t.Fatal(err)
	}
	if _, err := db.Exec(
		`INSERT INTO goose_db_version (version_id, is_applied) VALUES (9999, 1)`,
	); err != nil {
		t.Fatal(err)
	}

	if _, err := store.StepUp(ctx, m, 0); err == nil ||
		!strings.Contains(err.Error(), "newer build") {
		t.Errorf("up: err = %v, want a newer-build error", err)
	}
	if _, err := store.StepDown(ctx, m, 1, false); err == nil ||
		!strings.Contains(err.Error(), "newer build") {
		t.Errorf("down: err = %v, want a newer-build error", err)
	}
}

func TestFailedMigrationIsRolledBack(t *testing.T) {
	ctx := context.Background()
	m, db := newMigrator(t)

	if _, err := store.StepUp(ctx, m, 1); err != nil {
		t.Fatal(err)
	}

	// Occupy migration 4's table name with a view. Its CREATE TABLE IF NOT
	// EXISTS then skips, and the CREATE INDEX that follows fails because
	// views can't be indexed, part-way through the migration.
	if _, err := db.Exec(
		`CREATE VIEW classification_codes AS SELECT 1 AS x`,
	); err != nil {
		t.Fatal(err)
	}

	_, err := store.StepUp(ctx, m, 0)
	if err == nil {
		t.Fatal("expected migration 4 to fail")
	}
	if v := version(t, m); v != 3 {
		t.Errorf("version after failure: %d, want 3", v)
	}
	var indexes int
	query := `SELECT count(*) FROM sqlite_master
		WHERE name LIKE 'classification_codes_%'`
	db.QueryRow(query).Scan(&indexes)
	if indexes != 0 {
		t.Errorf("failed migration left %d objects behind", indexes)
	}
}