package tickets

import (
	"context"
	"fmt"
	"log/slog"
	"strings"
	"sync"
	"time"
	"unicode"

	"github.com/bwmarrin/discordgo"
	"github.com/leolionad58/ticketbot/internal/config"
	"github.com/leolionad58/ticketbot/internal/db"
)

type Service struct {
	db        *db.TicketRepo
	panelRepo *db.PanelConfigRepo
	auth      *AuthService
	session   *discordgo.Session
	cfg       *config.Provider
	opening   sync.Map // key: userID+":"+ticketType prevents double-click
}

func NewService(repo *db.TicketRepo, panelRepo *db.PanelConfigRepo, auth *AuthService, s *discordgo.Session, cfg *config.Provider) *Service {
	return &Service{db: repo, panelRepo: panelRepo, auth: auth, session: s, cfg: cfg}
}

var ErrAlreadyOpen = fmt.Errorf("already_open")

// Open creates a ticket channel and inserts into DB. Returns the created Ticket.
// Returns ErrAlreadyOpen (wrapped with channel ID) if user already has an open ticket of the same type.
func (svc *Service) Open(ctx context.Context, guildID, userID, panelName, ticketType string) (*db.Ticket, error) {
	lockKey := userID + ":" + ticketType
	if _, loaded := svc.opening.LoadOrStore(lockKey, struct{}{}); loaded {
		return nil, fmt.Errorf("creation already in progress")
	}
	defer svc.opening.Delete(lockKey)

	existing, err := svc.db.HasOpenTicket(ctx, userID, ticketType)
	if err != nil {
		return nil, fmt.Errorf("check existing: %w", err)
	}
	if existing != nil {
		return existing, fmt.Errorf("%w:%s", ErrAlreadyOpen, existing.ChannelID)
	}

	var categoryID, claimChannelID, logChannelID, staffRoleID string
	var claimReupMinutes int
	yamlCfg := svc.cfg.Get()
	if panel, ok := yamlCfg.Panels[panelName]; ok {
		typeCfg, ok := panel.Types[ticketType]
		if !ok {
			return nil, fmt.Errorf("type %q not found in panel %q", ticketType, panelName)
		}
		categoryID = typeCfg.Category
		staffRoleID = typeCfg.StaffRole
		// YAML panels have no per-type claim/log routing; fall back to global config at claim/log time
	} else if svc.panelRepo != nil {
		dbPanel, err := svc.panelRepo.GetByName(ctx, panelName)
		if err != nil || dbPanel == nil {
			return nil, fmt.Errorf("panel %q not found", panelName)
		}
		var dbType *db.PanelType
		for _, t := range dbPanel.Types {
			if t.Name == ticketType {
				dbType = t
				break
			}
		}
		if dbType == nil {
			return nil, fmt.Errorf("type %q not found in panel %q", ticketType, panelName)
		}
		categoryID = dbType.CategoryID
		claimChannelID = dbType.ClaimChannelID
		logChannelID = dbType.LogChannelID
		staffRoleID = dbType.StaffRoleID
		claimReupMinutes = dbType.ClaimReupMinutes
	} else {
		return nil, fmt.Errorf("panel %q not found", panelName)
	}

	// Reserve a placeholder to get the ticket number atomically
	ticket := &db.Ticket{
		UserID:           userID,
		Panel:            panelName,
		Type:             ticketType,
		ChannelID:        fmt.Sprintf("pending-%d", time.Now().UnixNano()),
		GuildID:          guildID,
		ClaimChannelID:   claimChannelID,
		LogChannelID:     logChannelID,
		StaffRoleID:      staffRoleID,
		ClaimReupMinutes: claimReupMinutes,
		OpenedAt:         time.Now(),
	}
	if err := svc.db.Insert(ctx, ticket); err != nil {
		return nil, fmt.Errorf("insert ticket: %w", err)
	}

	channelName := fmt.Sprintf("%s-%04d", ticketType, ticket.TicketNumber)
	ch, err := svc.session.GuildChannelCreateComplex(guildID, discordgo.GuildChannelCreateData{
		Name:     channelName,
		Type:     discordgo.ChannelTypeGuildText,
		ParentID: categoryID,
		PermissionOverwrites: []*discordgo.PermissionOverwrite{
			{
				ID:   guildID,
				Type: discordgo.PermissionOverwriteTypeRole,
				Deny: discordgo.PermissionViewChannel,
			},
			{
				ID:   userID,
				Type: discordgo.PermissionOverwriteTypeMember,
				Allow: discordgo.PermissionViewChannel |
					discordgo.PermissionSendMessages |
					discordgo.PermissionReadMessageHistory |
					discordgo.PermissionAttachFiles,
			},
		},
	})
	if err != nil {
		slog.Error("create channel", "ticket_id", ticket.ID, "err", err)
		return nil, fmt.Errorf("create channel: %w", err)
	}

	if err := svc.db.UpdateChannelID(ctx, ticket.ID, ch.ID); err != nil {
		slog.Error("update channel_id", "ticket_id", ticket.ID, "err", err)
	}
	ticket.ChannelID = ch.ID
	return ticket, nil
}

// AddMember adds a Discord user to a ticket channel with full read/send permissions.
func (svc *Service) AddMember(ctx context.Context, channelID, userID string) error {
	return svc.session.ChannelPermissionSet(channelID, userID,
		discordgo.PermissionOverwriteTypeMember,
		discordgo.PermissionViewChannel|discordgo.PermissionSendMessages|
			discordgo.PermissionReadMessageHistory|discordgo.PermissionAttachFiles,
		0)
}

// RemoveMember removes a Discord user from a ticket channel.
func (svc *Service) RemoveMember(ctx context.Context, channelID, userID string) error {
	return svc.session.ChannelPermissionDelete(channelID, userID)
}

// Rename sanitizes and renames a ticket channel. Returns error if name is invalid.
func (svc *Service) Rename(ctx context.Context, channelID, name string) error {
	safe := sanitizeChannelName(name)
	if safe == "" {
		return fmt.Errorf("invalid channel name after sanitization")
	}
	if len(safe) > 100 {
		safe = safe[:100]
	}
	_, err := svc.session.ChannelEdit(channelID, &discordgo.ChannelEdit{Name: safe})
	return err
}

// ClaimChannel adds a staff member to a ticket channel.
func (svc *Service) ClaimChannel(ctx context.Context, channelID, staffID string) error {
	return svc.AddMember(ctx, channelID, staffID)
}

// DeleteChannel permanently deletes a Discord channel.
func (svc *Service) DeleteChannel(channelID string) error {
	_, err := svc.session.ChannelDelete(channelID)
	return err
}

func sanitizeChannelName(name string) string {
	var b strings.Builder
	for _, r := range strings.ToLower(name) {
		switch {
		case r >= 'a' && r <= 'z', r >= '0' && r <= '9', r == '-', r == '_':
			b.WriteRune(r)
		case unicode.IsSpace(r):
			b.WriteRune('-')
		}
	}
	return strings.Trim(b.String(), "-")
}