package store

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"net/url"
	"path/filepath"
	"sync"
	"time"

	_ "modernc.org/sqlite"

	"banger/internal/model"
)

type Store struct {
	db      *sql.DB
	writeMu sync.Mutex
}

func Open(path string) (*Store, error) {
	dsn, err := sqliteDSN(path)
	if err != nil {
		return nil, err
	}
	db, err := sql.Open("sqlite", dsn)
	if err != nil {
		return nil, err
	}
	store := &Store{db: db}
	if err := store.migrate(); err != nil {
		_ = db.Close()
		return nil, err
	}
	return store, nil
}

func (s *Store) Close() error {
	return s.db.Close()
}

func sqliteDSN(path string) (string, error) {
	absPath, err := filepath.Abs(path)
	if err != nil {
		return "", fmt.Errorf("resolve sqlite path: %w", err)
	}
	query := url.Values{}
	for _, pragma := range []string{
		"journal_mode(WAL)",
		"synchronous(NORMAL)",
		"foreign_keys(1)",
		"busy_timeout(5000)",
		"temp_store(MEMORY)",
		"wal_autocheckpoint(1000)",
		"journal_size_limit(67108864)",
	} {
		query.Add("_pragma", pragma)
	}
	return (&url.URL{
		Scheme:   "file",
		Path:     filepath.ToSlash(absPath),
		RawQuery: query.Encode(),
	}).String(), nil
}

func (s *Store) migrate() error {
	stmts := []string{
		`CREATE TABLE IF NOT EXISTS images (
			id TEXT PRIMARY KEY,
			name TEXT NOT NULL UNIQUE,
			managed INTEGER NOT NULL DEFAULT 0,
			artifact_dir TEXT,
			rootfs_path TEXT NOT NULL,
			work_seed_path TEXT,
			kernel_path TEXT NOT NULL,
			initrd_path TEXT,
			modules_dir TEXT,
			packages_path TEXT,
			build_size TEXT,
			seeded_ssh_public_key_fingerprint TEXT,
			docker INTEGER NOT NULL DEFAULT 0,
			created_at TEXT NOT NULL,
			updated_at TEXT NOT NULL
		);`,
		`CREATE TABLE IF NOT EXISTS vms (
			id TEXT PRIMARY KEY,
			name TEXT NOT NULL UNIQUE,
			image_id TEXT NOT NULL,
			guest_ip TEXT NOT NULL UNIQUE,
			state TEXT NOT NULL,
			created_at TEXT NOT NULL,
			updated_at TEXT NOT NULL,
			last_touched_at TEXT NOT NULL,
			spec_json TEXT NOT NULL,
			runtime_json TEXT NOT NULL,
			stats_json TEXT NOT NULL DEFAULT '{}',
			FOREIGN KEY(image_id) REFERENCES images(id) ON DELETE RESTRICT
		);`,
		`CREATE TABLE IF NOT EXISTS guest_sessions (
			id TEXT PRIMARY KEY,
			vm_id TEXT NOT NULL,
			name TEXT NOT NULL,
			backend TEXT NOT NULL,
			command TEXT NOT NULL,
			args_json TEXT NOT NULL DEFAULT '[]',
			cwd TEXT,
			env_json TEXT NOT NULL DEFAULT '{}',
			stdin_mode TEXT NOT NULL,
			status TEXT NOT NULL,
			exit_code INTEGER,
			guest_pid INTEGER NOT NULL DEFAULT 0,
			guest_state_dir TEXT,
			stdout_log_path TEXT,
			stderr_log_path TEXT,
			tags_json TEXT NOT NULL DEFAULT '{}',
			last_error TEXT,
			attachable INTEGER NOT NULL DEFAULT 0,
			created_at TEXT NOT NULL,
			started_at TEXT,
			updated_at TEXT NOT NULL,
			ended_at TEXT,
			UNIQUE(vm_id, name),
			FOREIGN KEY(vm_id) REFERENCES vms(id) ON DELETE CASCADE
		);`,
	}
	for _, stmt := range stmts {
		if _, err := s.db.Exec(stmt); err != nil {
			return err
		}
	}
	if err := ensureColumnExists(s.db, "images", "work_seed_path", "TEXT"); err != nil {
		return err
	}
	if err := ensureColumnExists(s.db, "images", "seeded_ssh_public_key_fingerprint", "TEXT"); err != nil {
		return err
	}
	for _, spec := range []struct{ table, column, typ string }{
		{"guest_sessions", "attach_backend", "TEXT"},
		{"guest_sessions", "attach_mode", "TEXT"},
		{"guest_sessions", "reattachable", "INTEGER NOT NULL DEFAULT 0"},
		{"guest_sessions", "launch_stage", "TEXT"},
		{"guest_sessions", "launch_message", "TEXT"},
		{"guest_sessions", "launch_raw_log", "TEXT"},
	} {
		if err := ensureColumnExists(s.db, spec.table, spec.column, spec.typ); err != nil {
			return err
		}
	}
	return nil
}

func (s *Store) UpsertImage(ctx context.Context, image model.Image) error {
	s.writeMu.Lock()
	defer s.writeMu.Unlock()
	const query = `
	INSERT INTO images (
		id, name, managed, artifact_dir, rootfs_path, work_seed_path, kernel_path, initrd_path,
		modules_dir, build_size, seeded_ssh_public_key_fingerprint, docker, created_at, updated_at
	) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
	ON CONFLICT(id) DO UPDATE SET
		name=excluded.name,
		managed=excluded.managed,
		artifact_dir=excluded.artifact_dir,
		rootfs_path=excluded.rootfs_path,
		work_seed_path=excluded.work_seed_path,
		kernel_path=excluded.kernel_path,
		initrd_path=excluded.initrd_path,
		modules_dir=excluded.modules_dir,
		build_size=excluded.build_size,
		seeded_ssh_public_key_fingerprint=excluded.seeded_ssh_public_key_fingerprint,
		docker=excluded.docker,
		updated_at=excluded.updated_at`
	_, err := s.db.ExecContext(ctx, query,
		image.ID,
		image.Name,
		boolToInt(image.Managed),
		image.ArtifactDir,
		image.RootfsPath,
		image.WorkSeedPath,
		image.KernelPath,
		image.InitrdPath,
		image.ModulesDir,
		image.BuildSize,
		image.SeededSSHPublicKeyFingerprint,
		boolToInt(image.Docker),
		image.CreatedAt.Format(time.RFC3339),
		image.UpdatedAt.Format(time.RFC3339),
	)
	return err
}

func (s *Store) GetImageByName(ctx context.Context, name string) (model.Image, error) {
	return s.getImage(ctx, "SELECT id, name, managed, artifact_dir, rootfs_path, work_seed_path, kernel_path, initrd_path, modules_dir, build_size, seeded_ssh_public_key_fingerprint, docker, created_at, updated_at FROM images WHERE name = ?", name)
}

func (s *Store) GetImageByID(ctx context.Context, id string) (model.Image, error) {
	return s.getImage(ctx, "SELECT id, name, managed, artifact_dir, rootfs_path, work_seed_path, kernel_path, initrd_path, modules_dir, build_size, seeded_ssh_public_key_fingerprint, docker, created_at, updated_at FROM images WHERE id = ?", id)
}

func (s *Store) ListImages(ctx context.Context) ([]model.Image, error) {
	rows, err := s.db.QueryContext(ctx, "SELECT id, name, managed, artifact_dir, rootfs_path, work_seed_path, kernel_path, initrd_path, modules_dir, build_size, seeded_ssh_public_key_fingerprint, docker, created_at, updated_at FROM images ORDER BY created_at ASC")
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var images []model.Image
	for rows.Next() {
		image, err := scanImage(rows)
		if err != nil {
			return nil, err
		}
		images = append(images, image)
	}
	return images, rows.Err()
}

func (s *Store) DeleteImage(ctx context.Context, id string) error {
	s.writeMu.Lock()
	defer s.writeMu.Unlock()
	_, err := s.db.ExecContext(ctx, "DELETE FROM images WHERE id = ?", id)
	return err
}

func (s *Store) UpsertVM(ctx context.Context, vm model.VMRecord) error {
	s.writeMu.Lock()
	defer s.writeMu.Unlock()
	specJSON, err := json.Marshal(vm.Spec)
	if err != nil {
		return err
	}
	runtimeJSON, err := json.Marshal(vm.Runtime)
	if err != nil {
		return err
	}
	statsJSON, err := json.Marshal(vm.Stats)
	if err != nil {
		return err
	}
	const query = `
	INSERT INTO vms (
		id, name, image_id, guest_ip, state, created_at, updated_at, last_touched_at,
		spec_json, runtime_json, stats_json
	) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
	ON CONFLICT(id) DO UPDATE SET
		name=excluded.name,
		image_id=excluded.image_id,
		guest_ip=excluded.guest_ip,
		state=excluded.state,
		updated_at=excluded.updated_at,
		last_touched_at=excluded.last_touched_at,
		spec_json=excluded.spec_json,
		runtime_json=excluded.runtime_json,
		stats_json=excluded.stats_json`
	_, err = s.db.ExecContext(ctx, query,
		vm.ID,
		vm.Name,
		vm.ImageID,
		vm.Runtime.GuestIP,
		string(vm.State),
		vm.CreatedAt.Format(time.RFC3339),
		vm.UpdatedAt.Format(time.RFC3339),
		vm.LastTouchedAt.Format(time.RFC3339),
		string(specJSON),
		string(runtimeJSON),
		string(statsJSON),
	)
	return err
}

func (s *Store) GetVM(ctx context.Context, idOrName string) (model.VMRecord, error) {
	const query = `
	SELECT id, name, image_id, guest_ip, state, created_at, updated_at, last_touched_at,
	       spec_json, runtime_json, stats_json
	FROM vms
	WHERE id = ? OR name = ?
	`
	row := s.db.QueryRowContext(ctx, query, idOrName, idOrName)
	return scanVMRow(row)
}

func (s *Store) GetVMByID(ctx context.Context, id string) (model.VMRecord, error) {
	row := s.db.QueryRowContext(ctx, `
	SELECT id, name, image_id, guest_ip, state, created_at, updated_at, last_touched_at,
	       spec_json, runtime_json, stats_json
	FROM vms WHERE id = ?`, id)
	return scanVMRow(row)
}

func (s *Store) ListVMs(ctx context.Context) ([]model.VMRecord, error) {
	rows, err := s.db.QueryContext(ctx, `
	SELECT id, name, image_id, guest_ip, state, created_at, updated_at, last_touched_at,
	       spec_json, runtime_json, stats_json
	FROM vms ORDER BY created_at ASC`)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var vms []model.VMRecord
	for rows.Next() {
		vm, err := scanVMRows(rows)
		if err != nil {
			return nil, err
		}
		vms = append(vms, vm)
	}
	return vms, rows.Err()
}

func (s *Store) DeleteVM(ctx context.Context, id string) error {
	s.writeMu.Lock()
	defer s.writeMu.Unlock()
	_, err := s.db.ExecContext(ctx, "DELETE FROM vms WHERE id = ?", id)
	return err
}

func (s *Store) FindVMsUsingImage(ctx context.Context, imageID string) ([]model.VMRecord, error) {
	rows, err := s.db.QueryContext(ctx, `
	SELECT id, name, image_id, guest_ip, state, created_at, updated_at, last_touched_at,
	       spec_json, runtime_json, stats_json
	FROM vms WHERE image_id = ?`, imageID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var vms []model.VMRecord
	for rows.Next() {
		vm, err := scanVMRows(rows)
		if err != nil {
			return nil, err
		}
		vms = append(vms, vm)
	}
	return vms, rows.Err()
}

func (s *Store) UpsertGuestSession(ctx context.Context, session model.GuestSession) error {
	s.writeMu.Lock()
	defer s.writeMu.Unlock()
	argsJSON, err := json.Marshal(session.Args)
	if err != nil {
		return err
	}
	envJSON, err := json.Marshal(session.Env)
	if err != nil {
		return err
	}
	tagsJSON, err := json.Marshal(session.Tags)
	if err != nil {
		return err
	}
	const query = `
	INSERT INTO guest_sessions (
		id, vm_id, name, backend, attach_backend, attach_mode, command, args_json, cwd, env_json, stdin_mode, status,
		exit_code, guest_pid, guest_state_dir, stdout_log_path, stderr_log_path, tags_json,
		last_error, attachable, reattachable, launch_stage, launch_message, launch_raw_log,
		created_at, started_at, updated_at, ended_at
	) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
	ON CONFLICT(id) DO UPDATE SET
		vm_id=excluded.vm_id,
		name=excluded.name,
		backend=excluded.backend,
		attach_backend=excluded.attach_backend,
		attach_mode=excluded.attach_mode,
		command=excluded.command,
		args_json=excluded.args_json,
		cwd=excluded.cwd,
		env_json=excluded.env_json,
		stdin_mode=excluded.stdin_mode,
		status=excluded.status,
		exit_code=excluded.exit_code,
		guest_pid=excluded.guest_pid,
		guest_state_dir=excluded.guest_state_dir,
		stdout_log_path=excluded.stdout_log_path,
		stderr_log_path=excluded.stderr_log_path,
		tags_json=excluded.tags_json,
		last_error=excluded.last_error,
		attachable=excluded.attachable,
		reattachable=excluded.reattachable,
		launch_stage=excluded.launch_stage,
		launch_message=excluded.launch_message,
		launch_raw_log=excluded.launch_raw_log,
		started_at=excluded.started_at,
		updated_at=excluded.updated_at,
		ended_at=excluded.ended_at`
	_, err = s.db.ExecContext(ctx, query,
		session.ID,
		session.VMID,
		session.Name,
		session.Backend,
		session.AttachBackend,
		session.AttachMode,
		session.Command,
		string(argsJSON),
		session.CWD,
		string(envJSON),
		string(session.StdinMode),
		string(session.Status),
		nullableInt(session.ExitCode),
		session.GuestPID,
		session.GuestStateDir,
		session.StdoutLogPath,
		session.StderrLogPath,
		string(tagsJSON),
		session.LastError,
		boolToInt(session.Attachable),
		boolToInt(session.Reattachable),
		session.LaunchStage,
		session.LaunchMessage,
		session.LaunchRawLog,
		session.CreatedAt.Format(time.RFC3339),
		nullableTimeString(session.StartedAt),
		session.UpdatedAt.Format(time.RFC3339),
		nullableTimeString(session.EndedAt),
	)
	return err
}

func (s *Store) GetGuestSessionByID(ctx context.Context, id string) (model.GuestSession, error) {
	row := s.db.QueryRowContext(ctx, guestSessionSelectSQL+" WHERE id = ?", id)
	return scanGuestSessionRow(row)
}

func (s *Store) GetGuestSession(ctx context.Context, vmID, idOrName string) (model.GuestSession, error) {
	row := s.db.QueryRowContext(ctx, guestSessionSelectSQL+" WHERE vm_id = ? AND (id = ? OR name = ?)", vmID, idOrName, idOrName)
	return scanGuestSessionRow(row)
}

func (s *Store) ListGuestSessionsByVM(ctx context.Context, vmID string) ([]model.GuestSession, error) {
	rows, err := s.db.QueryContext(ctx, guestSessionSelectSQL+" WHERE vm_id = ? ORDER BY created_at ASC", vmID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var sessions []model.GuestSession
	for rows.Next() {
		session, err := scanGuestSession(rows)
		if err != nil {
			return nil, err
		}
		sessions = append(sessions, session)
	}
	return sessions, rows.Err()
}

func (s *Store) DeleteGuestSession(ctx context.Context, id string) error {
	s.writeMu.Lock()
	defer s.writeMu.Unlock()
	_, err := s.db.ExecContext(ctx, "DELETE FROM guest_sessions WHERE id = ?", id)
	return err
}

func (s *Store) NextGuestIP(ctx context.Context, bridgeIPPrefix string) (string, error) {
	used := map[string]struct{}{}
	rows, err := s.db.QueryContext(ctx, "SELECT guest_ip FROM vms")
	if err != nil {
		return "", err
	}
	defer rows.Close()
	for rows.Next() {
		var ip string
		if err := rows.Scan(&ip); err != nil {
			return "", err
		}
		used[ip] = struct{}{}
	}
	if err := rows.Err(); err != nil {
		return "", err
	}
	for i := 2; i < 255; i++ {
		candidate := fmt.Sprintf("%s.%d", bridgeIPPrefix, i)
		if _, exists := used[candidate]; !exists {
			return candidate, nil
		}
	}
	return "", errors.New("no guest IPs available")
}

func (s *Store) getImage(ctx context.Context, query string, arg string) (model.Image, error) {
	row := s.db.QueryRowContext(ctx, query, arg)
	return scanImageRow(row)
}

func scanImage(rows scanner) (model.Image, error) {
	return scanImageRow(rows)
}

type scanner interface {
	Scan(dest ...any) error
}

func scanImageRow(row scanner) (model.Image, error) {
	var image model.Image
	var managed, docker int
	var workSeedPath sql.NullString
	var seededSSHPublicKeyFingerprint sql.NullString
	var createdAt, updatedAt string
	err := row.Scan(
		&image.ID,
		&image.Name,
		&managed,
		&image.ArtifactDir,
		&image.RootfsPath,
		&workSeedPath,
		&image.KernelPath,
		&image.InitrdPath,
		&image.ModulesDir,
		&image.BuildSize,
		&seededSSHPublicKeyFingerprint,
		&docker,
		&createdAt,
		&updatedAt,
	)
	if err != nil {
		return image, err
	}
	image.Managed = managed == 1
	image.Docker = docker == 1
	image.WorkSeedPath = workSeedPath.String
	image.SeededSSHPublicKeyFingerprint = seededSSHPublicKeyFingerprint.String
	image.CreatedAt, err = time.Parse(time.RFC3339, createdAt)
	if err != nil {
		return image, err
	}
	image.UpdatedAt, err = time.Parse(time.RFC3339, updatedAt)
	if err != nil {
		return image, err
	}
	return image, nil
}

func scanVMRow(row scanner) (model.VMRecord, error) {
	return scanVMInto(row)
}

func scanVMRows(rows scanner) (model.VMRecord, error) {
	return scanVMInto(rows)
}

func scanVMInto(row scanner) (model.VMRecord, error) {
	var vm model.VMRecord
	var state, createdAt, updatedAt, touchedAt, specJSON, runtimeJSON, statsJSON string
	err := row.Scan(
		&vm.ID,
		&vm.Name,
		&vm.ImageID,
		&vm.Runtime.GuestIP,
		&state,
		&createdAt,
		&updatedAt,
		&touchedAt,
		&specJSON,
		&runtimeJSON,
		&statsJSON,
	)
	if err != nil {
		return vm, err
	}
	vm.State = model.VMState(state)
	if err := json.Unmarshal([]byte(specJSON), &vm.Spec); err != nil {
		return vm, err
	}
	if err := json.Unmarshal([]byte(runtimeJSON), &vm.Runtime); err != nil {
		return vm, err
	}
	if statsJSON != "" {
		if err := json.Unmarshal([]byte(statsJSON), &vm.Stats); err != nil {
			return vm, err
		}
	}
	var parseErr error
	vm.CreatedAt, parseErr = time.Parse(time.RFC3339, createdAt)
	if parseErr != nil {
		return vm, parseErr
	}
	vm.UpdatedAt, parseErr = time.Parse(time.RFC3339, updatedAt)
	if parseErr != nil {
		return vm, parseErr
	}
	vm.LastTouchedAt, parseErr = time.Parse(time.RFC3339, touchedAt)
	if parseErr != nil {
		return vm, parseErr
	}
	return vm, nil
}

func ensureColumnExists(db *sql.DB, table, column, columnType string) error {
	rows, err := db.Query(fmt.Sprintf("PRAGMA table_info(%s)", table))
	if err != nil {
		return err
	}
	defer rows.Close()
	for rows.Next() {
		var (
			cid       int
			name      string
			valueType string
			notNull   int
			defaultV  sql.NullString
			pk        int
		)
		if err := rows.Scan(&cid, &name, &valueType, &notNull, &defaultV, &pk); err != nil {
			return err
		}
		if name == column {
			return nil
		}
	}
	if err := rows.Err(); err != nil {
		return err
	}
	_, err = db.Exec(fmt.Sprintf("ALTER TABLE %s ADD COLUMN %s %s", table, column, columnType))
	return err
}

func boolToInt(value bool) int {
	if value {
		return 1
	}
	return 0
}

const guestSessionSelectSQL = `
SELECT id, vm_id, name, backend, attach_backend, attach_mode, command, args_json, cwd, env_json, stdin_mode, status,
       exit_code, guest_pid, guest_state_dir, stdout_log_path, stderr_log_path, tags_json,
       last_error, attachable, reattachable, launch_stage, launch_message, launch_raw_log,
       created_at, started_at, updated_at, ended_at
FROM guest_sessions`

func scanGuestSession(rows scanner) (model.GuestSession, error) {
	return scanGuestSessionRow(rows)
}

func scanGuestSessionRow(row scanner) (model.GuestSession, error) {
	var session model.GuestSession
	var (
		argsJSON     string
		envJSON      string
		tagsJSON     string
		stdinMode    string
		status       string
		exitCode     sql.NullInt64
		startedAt    sql.NullString
		endedAt      sql.NullString
		attachable   int
		reattachable int
		createdRaw   string
		updatedRaw   string
	)
	err := row.Scan(
		&session.ID,
		&session.VMID,
		&session.Name,
		&session.Backend,
		&session.AttachBackend,
		&session.AttachMode,
		&session.Command,
		&argsJSON,
		&session.CWD,
		&envJSON,
		&stdinMode,
		&status,
		&exitCode,
		&session.GuestPID,
		&session.GuestStateDir,
		&session.StdoutLogPath,
		&session.StderrLogPath,
		&tagsJSON,
		&session.LastError,
		&attachable,
		&reattachable,
		&session.LaunchStage,
		&session.LaunchMessage,
		&session.LaunchRawLog,
		&createdRaw,
		&startedAt,
		&updatedRaw,
		&endedAt,
	)
	if err != nil {
		return session, err
	}
	session.StdinMode = model.GuestSessionStdinMode(stdinMode)
	session.Status = model.GuestSessionStatus(status)
	session.Attachable = attachable == 1
	session.Reattachable = reattachable == 1
	if argsJSON != "" {
		if err := json.Unmarshal([]byte(argsJSON), &session.Args); err != nil {
			return session, err
		}
	}
	if envJSON != "" {
		if err := json.Unmarshal([]byte(envJSON), &session.Env); err != nil {
			return session, err
		}
	}
	if tagsJSON != "" {
		if err := json.Unmarshal([]byte(tagsJSON), &session.Tags); err != nil {
			return session, err
		}
	}
	if exitCode.Valid {
		value := int(exitCode.Int64)
		session.ExitCode = &value
	}
	var parseErr error
	session.CreatedAt, parseErr = time.Parse(time.RFC3339, createdRaw)
	if parseErr != nil {
		return session, parseErr
	}
	session.UpdatedAt, parseErr = time.Parse(time.RFC3339, updatedRaw)
	if parseErr != nil {
		return session, parseErr
	}
	if startedAt.Valid && startedAt.String != "" {
		session.StartedAt, parseErr = time.Parse(time.RFC3339, startedAt.String)
		if parseErr != nil {
			return session, parseErr
		}
	}
	if endedAt.Valid && endedAt.String != "" {
		session.EndedAt, parseErr = time.Parse(time.RFC3339, endedAt.String)
		if parseErr != nil {
			return session, parseErr
		}
	}
	return session, nil
}

func nullableTimeString(value time.Time) any {
	if value.IsZero() {
		return nil
	}
	return value.Format(time.RFC3339)
}

func nullableInt(value *int) any {
	if value == nil {
		return nil
	}
	return *value
}