package store

import (
	"errors"
	"time"

	"github.com/jackc/pgx/v5/pgconn"
	"github.com/jackc/pgx/v5/pgxpool"
)

// ErrLastAdmin is returned by DeleteUser when attempting to delete the last admin.
var ErrLastAdmin = errors.New("cannot delete the last admin")

// ErrUniqueViolation is a sentinel for PostgreSQL unique constraint violations.
var ErrUniqueViolation = errors.New("unique violation")

// IsUniqueViolation reports whether err is a PostgreSQL unique constraint violation (23505).
func IsUniqueViolation(err error) bool {
	var pgErr *pgconn.PgError
	return errors.As(err, &pgErr) && pgErr.Code == "23505"
}

// Store provides database access. The pool is unexported; all access goes through methods.
type Store struct{ p *pgxpool.Pool }

func New(p *pgxpool.Pool) *Store { return &Store{p: p} }

// ---------- types ----------

type User struct {
	ID           int64
	Username     string
	PasswordHash string
	Role         string
	CreatedAt    time.Time
}

type Library struct {
	ID        int64
	Name      string
	RootPath  string
	CreatedAt time.Time
}

type Book struct {
	ID, LibraryID int64
	Path          string
	Title         string
	Format        string
	FileSize      int64
	ModTS         int64
	PageCount     int // 0 means unknown (pdf/epub/txt)
	State         string
	ErrMsg        string
	AddedAt       time.Time
}

type BookMeta struct {
	ID     int64
	Size   int64
	ModTS  int64
	Format string
}

type BookView struct {
	Book
	LibraryName string
	Percent     float64
}

type Progress struct {
	LibraryID   int64
	LibraryName string
	BookPath    string
	Title       string // empty when book deleted
	Locator     []byte
	Percent     float64
	UpdatedAt   time.Time
}

type Bookmark struct {
	ID        int64
	LibraryID int64
	BookPath  string
	Locator   []byte
	Percent   float64
	Note      string
	CreatedAt time.Time
}

// Pool returns the underlying pool for test setup only.
// Production code should use Store methods exclusively.
func (s *Store) Pool() *pgxpool.Pool { return s.p }