// Package template provides CRUD operations for tournament building blocks:
// chip sets, payout structures, buy-in configs, and tournament templates.
package template

import (
	"context"
	"database/sql"
	"fmt"
	"time"
)

// ChipSet represents a collection of chip denominations used in tournaments.
type ChipSet struct {
	ID            int64              `json:"id"`
	Name          string             `json:"name"`
	IsBuiltin     bool               `json:"is_builtin"`
	Denominations []ChipDenomination `json:"denominations,omitempty"`
	CreatedAt     time.Time          `json:"created_at"`
	UpdatedAt     time.Time          `json:"updated_at"`
}

// ChipDenomination represents a single chip denomination within a chip set.
type ChipDenomination struct {
	ID        int64  `json:"id,omitempty"`
	ChipSetID int64  `json:"chip_set_id,omitempty"`
	Value     int64  `json:"value"`
	ColorHex  string `json:"color_hex"`
	Label     string `json:"label"`
	SortOrder int    `json:"sort_order"`
}

// ChipSetService provides CRUD operations for chip sets.
type ChipSetService struct {
	db *sql.DB
}

// NewChipSetService creates a new ChipSetService.
func NewChipSetService(db *sql.DB) *ChipSetService {
	return &ChipSetService{db: db}
}

// CreateChipSet creates a new chip set with its denominations.
func (s *ChipSetService) CreateChipSet(ctx context.Context, name string, denominations []ChipDenomination) (*ChipSet, error) {
	if name == "" {
		return nil, fmt.Errorf("chip set name is required")
	}
	if len(denominations) == 0 {
		return nil, fmt.Errorf("at least one denomination is required")
	}

	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return nil, fmt.Errorf("begin transaction: %w", err)
	}
	defer tx.Rollback()

	now := time.Now().Unix()
	res, err := tx.ExecContext(ctx,
		"INSERT INTO chip_sets (name, is_builtin, created_at, updated_at) VALUES (?, 0, ?, ?)",
		name, now, now,
	)
	if err != nil {
		return nil, fmt.Errorf("insert chip set: %w", err)
	}
	id, err := res.LastInsertId()
	if err != nil {
		return nil, fmt.Errorf("get chip set id: %w", err)
	}

	for i, d := range denominations {
		if d.Value <= 0 {
			return nil, fmt.Errorf("denomination %d: value must be positive", i)
		}
		_, err := tx.ExecContext(ctx,
			"INSERT INTO chip_denominations (chip_set_id, value, color_hex, label, sort_order) VALUES (?, ?, ?, ?, ?)",
			id, d.Value, d.ColorHex, d.Label, d.SortOrder,
		)
		if err != nil {
			return nil, fmt.Errorf("insert denomination %d: %w", i, err)
		}
	}

	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("commit: %w", err)
	}

	return s.GetChipSet(ctx, id)
}

// GetChipSet retrieves a chip set by ID, including its denominations.
func (s *ChipSetService) GetChipSet(ctx context.Context, id int64) (*ChipSet, error) {
	cs := &ChipSet{}
	var createdAt, updatedAt int64
	var isBuiltin int

	err := s.db.QueryRowContext(ctx,
		"SELECT id, name, is_builtin, created_at, updated_at FROM chip_sets WHERE id = ?", id,
	).Scan(&cs.ID, &cs.Name, &isBuiltin, &createdAt, &updatedAt)
	if err == sql.ErrNoRows {
		return nil, fmt.Errorf("chip set not found: %d", id)
	}
	if err != nil {
		return nil, fmt.Errorf("get chip set: %w", err)
	}
	cs.IsBuiltin = isBuiltin != 0
	cs.CreatedAt = time.Unix(createdAt, 0)
	cs.UpdatedAt = time.Unix(updatedAt, 0)

	rows, err := s.db.QueryContext(ctx,
		"SELECT id, chip_set_id, value, color_hex, label, sort_order FROM chip_denominations WHERE chip_set_id = ? ORDER BY sort_order",
		id,
	)
	if err != nil {
		return nil, fmt.Errorf("get denominations: %w", err)
	}
	defer rows.Close()

	for rows.Next() {
		var d ChipDenomination
		if err := rows.Scan(&d.ID, &d.ChipSetID, &d.Value, &d.ColorHex, &d.Label, &d.SortOrder); err != nil {
			return nil, fmt.Errorf("scan denomination: %w", err)
		}
		cs.Denominations = append(cs.Denominations, d)
	}
	if err := rows.Err(); err != nil {
		return nil, fmt.Errorf("iterate denominations: %w", err)
	}

	return cs, nil
}

// ListChipSets returns all chip sets (without denominations for list performance).
func (s *ChipSetService) ListChipSets(ctx context.Context) ([]ChipSet, error) {
	rows, err := s.db.QueryContext(ctx,
		"SELECT id, name, is_builtin, created_at, updated_at FROM chip_sets ORDER BY is_builtin DESC, name",
	)
	if err != nil {
		return nil, fmt.Errorf("list chip sets: %w", err)
	}
	defer rows.Close()

	var sets []ChipSet
	for rows.Next() {
		var cs ChipSet
		var isBuiltin int
		var createdAt, updatedAt int64
		if err := rows.Scan(&cs.ID, &cs.Name, &isBuiltin, &createdAt, &updatedAt); err != nil {
			return nil, fmt.Errorf("scan chip set: %w", err)
		}
		cs.IsBuiltin = isBuiltin != 0
		cs.CreatedAt = time.Unix(createdAt, 0)
		cs.UpdatedAt = time.Unix(updatedAt, 0)
		sets = append(sets, cs)
	}
	return sets, rows.Err()
}

// UpdateChipSet updates a chip set name and replaces its denominations.
func (s *ChipSetService) UpdateChipSet(ctx context.Context, id int64, name string, denominations []ChipDenomination) error {
	if name == "" {
		return fmt.Errorf("chip set name is required")
	}
	if len(denominations) == 0 {
		return fmt.Errorf("at least one denomination is required")
	}

	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("begin transaction: %w", err)
	}
	defer tx.Rollback()

	now := time.Now().Unix()
	res, err := tx.ExecContext(ctx,
		"UPDATE chip_sets SET name = ?, updated_at = ? WHERE id = ?",
		name, now, id,
	)
	if err != nil {
		return fmt.Errorf("update chip set: %w", err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("chip set not found: %d", id)
	}

	// Replace denominations: delete old, insert new
	if _, err := tx.ExecContext(ctx, "DELETE FROM chip_denominations WHERE chip_set_id = ?", id); err != nil {
		return fmt.Errorf("delete old denominations: %w", err)
	}

	for i, d := range denominations {
		if d.Value <= 0 {
			return fmt.Errorf("denomination %d: value must be positive", i)
		}
		_, err := tx.ExecContext(ctx,
			"INSERT INTO chip_denominations (chip_set_id, value, color_hex, label, sort_order) VALUES (?, ?, ?, ?, ?)",
			id, d.Value, d.ColorHex, d.Label, d.SortOrder,
		)
		if err != nil {
			return fmt.Errorf("insert denomination %d: %w", i, err)
		}
	}

	return tx.Commit()
}

// DeleteChipSet deletes a chip set. Built-in chip sets cannot be deleted.
// Returns an error if the chip set is referenced by active tournaments.
func (s *ChipSetService) DeleteChipSet(ctx context.Context, id int64) error {
	// Check if builtin
	var isBuiltin int
	err := s.db.QueryRowContext(ctx, "SELECT is_builtin FROM chip_sets WHERE id = ?", id).Scan(&isBuiltin)
	if err == sql.ErrNoRows {
		return fmt.Errorf("chip set not found: %d", id)
	}
	if err != nil {
		return fmt.Errorf("check chip set: %w", err)
	}
	if isBuiltin != 0 {
		return fmt.Errorf("cannot delete built-in chip set")
	}

	// Check if referenced by active tournaments
	var refCount int
	err = s.db.QueryRowContext(ctx,
		"SELECT COUNT(*) FROM tournaments WHERE chip_set_id = ? AND status NOT IN ('completed', 'cancelled')", id,
	).Scan(&refCount)
	if err != nil {
		return fmt.Errorf("check references: %w", err)
	}
	if refCount > 0 {
		return fmt.Errorf("chip set is referenced by %d active tournament(s)", refCount)
	}

	res, err := s.db.ExecContext(ctx, "DELETE FROM chip_sets WHERE id = ?", id)
	if err != nil {
		return fmt.Errorf("delete chip set: %w", err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("chip set not found: %d", id)
	}
	return nil
}

// DuplicateChipSet creates an independent copy of a chip set with a new name.
func (s *ChipSetService) DuplicateChipSet(ctx context.Context, id int64, newName string) (*ChipSet, error) {
	original, err := s.GetChipSet(ctx, id)
	if err != nil {
		return nil, fmt.Errorf("get original: %w", err)
	}

	if newName == "" {
		newName = original.Name + " (Copy)"
	}

	return s.CreateChipSet(ctx, newName, original.Denominations)
}