package template

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

	"github.com/felt-app/felt/internal/blind"
)

// TournamentTemplate composes building blocks into a reusable tournament configuration.
type TournamentTemplate struct {
	ID                    int64   `json:"id"`
	Name                  string  `json:"name"`
	Description           string  `json:"description"`
	ChipSetID             int64   `json:"chip_set_id"`
	BlindStructureID      int64   `json:"blind_structure_id"`
	PayoutStructureID     int64   `json:"payout_structure_id"`
	BuyinConfigID         int64   `json:"buyin_config_id"`
	PointsFormulaID       *int64  `json:"points_formula_id,omitempty"`
	MinPlayers            int     `json:"min_players"`
	MaxPlayers            *int    `json:"max_players,omitempty"`
	EarlySignupBonusChips int64   `json:"early_signup_bonus_chips"`
	EarlySignupCutoff     *string `json:"early_signup_cutoff,omitempty"`
	PunctualityBonusChips int64   `json:"punctuality_bonus_chips"`
	IsPKO                 bool    `json:"is_pko"`
	IsBuiltin             bool    `json:"is_builtin"`
	CreatedAt             time.Time `json:"created_at"`
	UpdatedAt             time.Time `json:"updated_at"`

	// Summary fields populated by GetTemplate (names only, not full data)
	ChipSetName        string `json:"chip_set_name,omitempty"`
	BlindStructureName string `json:"blind_structure_name,omitempty"`
	PayoutStructureName string `json:"payout_structure_name,omitempty"`
	BuyinConfigName    string `json:"buyin_config_name,omitempty"`
}

// ExpandedTemplate returns a template with ALL building block data populated.
type ExpandedTemplate struct {
	TournamentTemplate
	ChipSet        *ChipSet              `json:"chip_set"`
	BlindStructure *blind.BlindStructure `json:"blind_structure"`
	PayoutStructure *PayoutStructure     `json:"payout_structure"`
	BuyinConfig    *BuyinConfig          `json:"buyin_config"`
}

// TournamentTemplateService provides CRUD operations for tournament templates.
type TournamentTemplateService struct {
	db      *sql.DB
	chips   *ChipSetService
	blinds  *blind.StructureService
	payouts *PayoutService
	buyins  *BuyinService
}

// NewTournamentTemplateService creates a new TournamentTemplateService.
func NewTournamentTemplateService(db *sql.DB) *TournamentTemplateService {
	return &TournamentTemplateService{
		db:      db,
		chips:   NewChipSetService(db),
		blinds:  blind.NewStructureService(db),
		payouts: NewPayoutService(db),
		buyins:  NewBuyinService(db),
	}
}

// CreateTemplate creates a new tournament template, validating all FK references exist.
func (s *TournamentTemplateService) CreateTemplate(ctx context.Context, tmpl *TournamentTemplate) (*TournamentTemplate, error) {
	if tmpl.Name == "" {
		return nil, fmt.Errorf("template name is required")
	}

	// Validate FK references exist
	if err := s.validateReferences(ctx, tmpl); err != nil {
		return nil, err
	}

	now := time.Now().Unix()
	isPKO := boolToInt(tmpl.IsPKO)

	res, err := s.db.ExecContext(ctx,
		`INSERT INTO tournament_templates (name, description, chip_set_id, blind_structure_id, payout_structure_id, buyin_config_id,
		 points_formula_id, min_players, max_players, early_signup_bonus_chips, early_signup_cutoff,
		 punctuality_bonus_chips, is_pko, is_builtin, created_at, updated_at)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 0, ?, ?)`,
		tmpl.Name, tmpl.Description, tmpl.ChipSetID, tmpl.BlindStructureID, tmpl.PayoutStructureID, tmpl.BuyinConfigID,
		tmpl.PointsFormulaID, tmpl.MinPlayers, tmpl.MaxPlayers, tmpl.EarlySignupBonusChips, tmpl.EarlySignupCutoff,
		tmpl.PunctualityBonusChips, isPKO, now, now,
	)
	if err != nil {
		return nil, fmt.Errorf("insert template: %w", err)
	}
	id, err := res.LastInsertId()
	if err != nil {
		return nil, fmt.Errorf("get template id: %w", err)
	}

	return s.GetTemplate(ctx, id)
}

// validateReferences checks that all FK references in a template point to existing entities.
func (s *TournamentTemplateService) validateReferences(ctx context.Context, tmpl *TournamentTemplate) error {
	// Check chip set exists
	var exists int
	if err := s.db.QueryRowContext(ctx, "SELECT COUNT(*) FROM chip_sets WHERE id = ?", tmpl.ChipSetID).Scan(&exists); err != nil || exists == 0 {
		return fmt.Errorf("chip set %d does not exist", tmpl.ChipSetID)
	}
	if err := s.db.QueryRowContext(ctx, "SELECT COUNT(*) FROM blind_structures WHERE id = ?", tmpl.BlindStructureID).Scan(&exists); err != nil || exists == 0 {
		return fmt.Errorf("blind structure %d does not exist", tmpl.BlindStructureID)
	}
	if err := s.db.QueryRowContext(ctx, "SELECT COUNT(*) FROM payout_structures WHERE id = ?", tmpl.PayoutStructureID).Scan(&exists); err != nil || exists == 0 {
		return fmt.Errorf("payout structure %d does not exist", tmpl.PayoutStructureID)
	}
	if err := s.db.QueryRowContext(ctx, "SELECT COUNT(*) FROM buyin_configs WHERE id = ?", tmpl.BuyinConfigID).Scan(&exists); err != nil || exists == 0 {
		return fmt.Errorf("buyin config %d does not exist", tmpl.BuyinConfigID)
	}
	if tmpl.PointsFormulaID != nil {
		if err := s.db.QueryRowContext(ctx, "SELECT COUNT(*) FROM points_formulas WHERE id = ?", *tmpl.PointsFormulaID).Scan(&exists); err != nil || exists == 0 {
			return fmt.Errorf("points formula %d does not exist", *tmpl.PointsFormulaID)
		}
	}
	return nil
}

// GetTemplate retrieves a template by ID with building block summary names.
func (s *TournamentTemplateService) GetTemplate(ctx context.Context, id int64) (*TournamentTemplate, error) {
	tmpl := &TournamentTemplate{}
	var createdAt, updatedAt int64
	var isPKO, isBuiltin int

	err := s.db.QueryRowContext(ctx,
		`SELECT t.id, t.name, t.description, t.chip_set_id, t.blind_structure_id, t.payout_structure_id, t.buyin_config_id,
		 t.points_formula_id, t.min_players, t.max_players, t.early_signup_bonus_chips, t.early_signup_cutoff,
		 t.punctuality_bonus_chips, t.is_pko, t.is_builtin, t.created_at, t.updated_at,
		 cs.name, bs.name, ps.name, bc.name
		 FROM tournament_templates t
		 JOIN chip_sets cs ON t.chip_set_id = cs.id
		 JOIN blind_structures bs ON t.blind_structure_id = bs.id
		 JOIN payout_structures ps ON t.payout_structure_id = ps.id
		 JOIN buyin_configs bc ON t.buyin_config_id = bc.id
		 WHERE t.id = ?`, id,
	).Scan(
		&tmpl.ID, &tmpl.Name, &tmpl.Description, &tmpl.ChipSetID, &tmpl.BlindStructureID, &tmpl.PayoutStructureID, &tmpl.BuyinConfigID,
		&tmpl.PointsFormulaID, &tmpl.MinPlayers, &tmpl.MaxPlayers, &tmpl.EarlySignupBonusChips, &tmpl.EarlySignupCutoff,
		&tmpl.PunctualityBonusChips, &isPKO, &isBuiltin, &createdAt, &updatedAt,
		&tmpl.ChipSetName, &tmpl.BlindStructureName, &tmpl.PayoutStructureName, &tmpl.BuyinConfigName,
	)
	if err == sql.ErrNoRows {
		return nil, fmt.Errorf("tournament template not found: %d", id)
	}
	if err != nil {
		return nil, fmt.Errorf("get template: %w", err)
	}
	tmpl.IsPKO = isPKO != 0
	tmpl.IsBuiltin = isBuiltin != 0
	tmpl.CreatedAt = time.Unix(createdAt, 0)
	tmpl.UpdatedAt = time.Unix(updatedAt, 0)

	return tmpl, nil
}

// GetTemplateExpanded retrieves a template with ALL building block data populated.
func (s *TournamentTemplateService) GetTemplateExpanded(ctx context.Context, id int64) (*ExpandedTemplate, error) {
	tmpl, err := s.GetTemplate(ctx, id)
	if err != nil {
		return nil, err
	}

	expanded := &ExpandedTemplate{TournamentTemplate: *tmpl}

	expanded.ChipSet, err = s.chips.GetChipSet(ctx, tmpl.ChipSetID)
	if err != nil {
		return nil, fmt.Errorf("expand chip set: %w", err)
	}

	expanded.BlindStructure, err = s.blinds.GetStructure(ctx, tmpl.BlindStructureID)
	if err != nil {
		return nil, fmt.Errorf("expand blind structure: %w", err)
	}

	expanded.PayoutStructure, err = s.payouts.GetPayoutStructure(ctx, tmpl.PayoutStructureID)
	if err != nil {
		return nil, fmt.Errorf("expand payout structure: %w", err)
	}

	expanded.BuyinConfig, err = s.buyins.GetBuyinConfig(ctx, tmpl.BuyinConfigID)
	if err != nil {
		return nil, fmt.Errorf("expand buyin config: %w", err)
	}

	return expanded, nil
}

// ListTemplates returns all tournament templates with building block summary names.
func (s *TournamentTemplateService) ListTemplates(ctx context.Context) ([]TournamentTemplate, error) {
	rows, err := s.db.QueryContext(ctx,
		`SELECT t.id, t.name, t.description, t.chip_set_id, t.blind_structure_id, t.payout_structure_id, t.buyin_config_id,
		 t.points_formula_id, t.min_players, t.max_players, t.early_signup_bonus_chips, t.early_signup_cutoff,
		 t.punctuality_bonus_chips, t.is_pko, t.is_builtin, t.created_at, t.updated_at,
		 cs.name, bs.name, ps.name, bc.name
		 FROM tournament_templates t
		 JOIN chip_sets cs ON t.chip_set_id = cs.id
		 JOIN blind_structures bs ON t.blind_structure_id = bs.id
		 JOIN payout_structures ps ON t.payout_structure_id = ps.id
		 JOIN buyin_configs bc ON t.buyin_config_id = bc.id
		 ORDER BY t.is_builtin DESC, t.name`,
	)
	if err != nil {
		return nil, fmt.Errorf("list templates: %w", err)
	}
	defer rows.Close()

	var templates []TournamentTemplate
	for rows.Next() {
		var tmpl TournamentTemplate
		var createdAt, updatedAt int64
		var isPKO, isBuiltin int
		if err := rows.Scan(
			&tmpl.ID, &tmpl.Name, &tmpl.Description, &tmpl.ChipSetID, &tmpl.BlindStructureID, &tmpl.PayoutStructureID, &tmpl.BuyinConfigID,
			&tmpl.PointsFormulaID, &tmpl.MinPlayers, &tmpl.MaxPlayers, &tmpl.EarlySignupBonusChips, &tmpl.EarlySignupCutoff,
			&tmpl.PunctualityBonusChips, &isPKO, &isBuiltin, &createdAt, &updatedAt,
			&tmpl.ChipSetName, &tmpl.BlindStructureName, &tmpl.PayoutStructureName, &tmpl.BuyinConfigName,
		); err != nil {
			return nil, fmt.Errorf("scan template: %w", err)
		}
		tmpl.IsPKO = isPKO != 0
		tmpl.IsBuiltin = isBuiltin != 0
		tmpl.CreatedAt = time.Unix(createdAt, 0)
		tmpl.UpdatedAt = time.Unix(updatedAt, 0)
		templates = append(templates, tmpl)
	}
	return templates, rows.Err()
}

// UpdateTemplate updates a tournament template.
func (s *TournamentTemplateService) UpdateTemplate(ctx context.Context, tmpl *TournamentTemplate) error {
	if tmpl.Name == "" {
		return fmt.Errorf("template name is required")
	}
	if err := s.validateReferences(ctx, tmpl); err != nil {
		return err
	}

	now := time.Now().Unix()
	isPKO := boolToInt(tmpl.IsPKO)

	res, err := s.db.ExecContext(ctx,
		`UPDATE tournament_templates SET name = ?, description = ?, chip_set_id = ?, blind_structure_id = ?,
		 payout_structure_id = ?, buyin_config_id = ?, points_formula_id = ?, min_players = ?, max_players = ?,
		 early_signup_bonus_chips = ?, early_signup_cutoff = ?, punctuality_bonus_chips = ?, is_pko = ?,
		 updated_at = ?
		 WHERE id = ?`,
		tmpl.Name, tmpl.Description, tmpl.ChipSetID, tmpl.BlindStructureID,
		tmpl.PayoutStructureID, tmpl.BuyinConfigID, tmpl.PointsFormulaID, tmpl.MinPlayers, tmpl.MaxPlayers,
		tmpl.EarlySignupBonusChips, tmpl.EarlySignupCutoff, tmpl.PunctualityBonusChips, isPKO,
		now, tmpl.ID,
	)
	if err != nil {
		return fmt.Errorf("update template: %w", err)
	}
	n, _ := res.RowsAffected()
	if n == 0 {
		return fmt.Errorf("tournament template not found: %d", tmpl.ID)
	}
	return nil
}

// DeleteTemplate deletes a tournament template. Built-in templates cannot be deleted.
func (s *TournamentTemplateService) DeleteTemplate(ctx context.Context, id int64) error {
	var isBuiltin int
	err := s.db.QueryRowContext(ctx, "SELECT is_builtin FROM tournament_templates WHERE id = ?", id).Scan(&isBuiltin)
	if err == sql.ErrNoRows {
		return fmt.Errorf("tournament template not found: %d", id)
	}
	if err != nil {
		return fmt.Errorf("check template: %w", err)
	}
	if isBuiltin != 0 {
		return fmt.Errorf("cannot delete built-in tournament template")
	}

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

// DuplicateTemplate creates an independent copy of a tournament template.
func (s *TournamentTemplateService) DuplicateTemplate(ctx context.Context, id int64, newName string) (*TournamentTemplate, error) {
	original, err := s.GetTemplate(ctx, id)
	if err != nil {
		return nil, fmt.Errorf("get original: %w", err)
	}

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

	copy := *original
	copy.ID = 0
	copy.Name = newName
	copy.IsBuiltin = false
	return s.CreateTemplate(ctx, &copy)
}

// SaveAsTemplate creates a new template from a tournament's current config.
func (s *TournamentTemplateService) SaveAsTemplate(ctx context.Context, tournamentID string, name string) (*TournamentTemplate, error) {
	if name == "" {
		return nil, fmt.Errorf("template name is required")
	}

	var tmpl TournamentTemplate
	var isPKO int

	err := s.db.QueryRowContext(ctx,
		`SELECT chip_set_id, blind_structure_id, payout_structure_id, buyin_config_id,
		 points_formula_id, min_players, max_players, early_signup_bonus_chips, early_signup_cutoff,
		 punctuality_bonus_chips, is_pko
		 FROM tournaments WHERE id = ?`, tournamentID,
	).Scan(
		&tmpl.ChipSetID, &tmpl.BlindStructureID, &tmpl.PayoutStructureID, &tmpl.BuyinConfigID,
		&tmpl.PointsFormulaID, &tmpl.MinPlayers, &tmpl.MaxPlayers, &tmpl.EarlySignupBonusChips, &tmpl.EarlySignupCutoff,
		&tmpl.PunctualityBonusChips, &isPKO,
	)
	if err == sql.ErrNoRows {
		return nil, fmt.Errorf("tournament not found: %s", tournamentID)
	}
	if err != nil {
		return nil, fmt.Errorf("get tournament config: %w", err)
	}

	tmpl.Name = name
	tmpl.IsPKO = isPKO != 0

	return s.CreateTemplate(ctx, &tmpl)
}