package main

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

// testDBPath returns a database path inside a fresh temp dir.
func testDBPath(t *testing.T) string {
	t.Helper()

	return filepath.Join(t.TempDir(), "db.sqlite")
}

// openTestDB creates a fresh scan database in a temp dir.
func openTestDB(t *testing.T) *sql.DB {
	t.Helper()

	db, err := openScanDatabase(testDBPath(t))
	if err != nil {
		t.Fatal(err)
	}

	t.Cleanup(func() { _ = db.Close() })

	return db
}

func TestDatabasePath(t *testing.T) {
	t.Setenv(databaseEnv, "")

	if got := databasePath(); got != defaultDatabasePath {
		t.Errorf("databasePath() = %q, want %q", got, defaultDatabasePath)
	}

	t.Setenv(databaseEnv, "/custom/place.sqlite")

	if got := databasePath(); got != "/custom/place.sqlite" {
		t.Errorf("databasePath() = %q, want the env override", got)
	}
}

func TestOpenScanDatabaseCreates(t *testing.T) {
	t.Parallel()

	// The parent directory does not exist yet; scan must create it.
	path := filepath.Join(t.TempDir(), "nested", "dir", "db.sqlite")

	db, err := openScanDatabase(path)
	if err != nil {
		t.Fatalf("openScanDatabase: %v", err)
	}

	v, err := userVersion(db)
	if err != nil || v != schemaVersion {
		t.Fatalf("userVersion = %d, %v; want %d, nil", v, err, schemaVersion)
	}

	_ = db.Close()

	// Reopening an existing database must succeed and find the schema.
	db, err = openScanDatabase(path)
	if err != nil {
		t.Fatalf("reopen: %v", err)
	}

	defer func() { _ = db.Close() }()

	recs, err := loadFileRows(db)
	if err != nil || len(recs) != 0 {
		t.Fatalf("loadFileRows = %v, %v; want empty, nil", recs, err)
	}
}

func TestOpenReportDatabaseMissing(t *testing.T) {
	t.Parallel()

	_, err := openReportDatabase(testDBPath(t))
	if !errors.Is(err, errNoDatabase) {
		t.Fatalf("err = %v, want errNoDatabase", err)
	}
}

func TestOpenReportDatabaseVersionMismatch(t *testing.T) {
	t.Parallel()

	path := testDBPath(t)

	db, err := openScanDatabase(path)
	if err != nil {
		t.Fatal(err)
	}

	_, err = db.ExecContext(context.Background(), "PRAGMA user_version = 99")
	if err != nil {
		t.Fatal(err)
	}

	_ = db.Close()

	_, err = openReportDatabase(path)
	if !errors.Is(err, errSchemaVersion) {
		t.Fatalf("err = %v, want errSchemaVersion", err)
	}
}

func TestOpenReportDatabaseOK(t *testing.T) {
	t.Parallel()

	path := testDBPath(t)

	db, err := openScanDatabase(path)
	if err != nil {
		t.Fatal(err)
	}

	_ = db.Close()

	db, err = openReportDatabase(path)
	if err != nil {
		t.Fatalf("openReportDatabase: %v", err)
	}

	_ = db.Close()
}

func TestApplyChangesRoundTrip(t *testing.T) {
	t.Parallel()

	db := openTestDB(t)

	// Paths may contain tabs and newlines; the database must store
	// them byte-exactly.
	recs := []scanRec{
		{size: 2, mtime: 20, head: "h2", tail: "t2", path: "/a/tab\tnew\nline"},
		{size: 1, mtime: 10, head: "h1", tail: "t1", path: "/a/x"},
	}

	err := applyChanges(db, recs, nil, newProgress("update", 2))
	if err != nil {
		t.Fatalf("applyChanges: %v", err)
	}

	got, err := loadFileRows(db)
	if err != nil {
		t.Fatal(err)
	}

	slices.SortFunc(got, func(a, b scanRec) int {
		return strings.Compare(a.path, b.path)
	})

	if !slices.Equal(got, recs) {
		t.Fatalf("rows = %+v, want %+v", got, recs)
	}

	// An upsert for an existing path updates in place; a delete
	// removes exactly its path.
	upd := scanRec{size: 3, mtime: 30, head: "h3", tail: "t3", path: "/a/x"}

	err = applyChanges(db, []scanRec{upd},
		[]string{"/a/tab\tnew\nline"}, newProgress("update", 2))
	if err != nil {
		t.Fatalf("applyChanges: %v", err)
	}

	got, err = loadFileRows(db)
	if err != nil {
		t.Fatal(err)
	}

	if len(got) != 1 || got[0] != upd {
		t.Fatalf("rows = %+v, want just %+v", got, upd)
	}
}