package social

import (
	"context"
	"fmt"
	"time"

	"github.com/google/uuid"

	"scrabble/backend/internal/account"
)

// AdminMessage is one chat message in the admin moderation list (Stage 17): the message
// plus its sender's resolved display name and source, for the operator console.
type AdminMessage struct {
	ID         uuid.UUID
	GameID     uuid.UUID
	SenderID   uuid.UUID
	SenderName string
	// Source is the sender's account kind: "guest", "robot", or its oldest identity kind
	// (e.g. "email", "telegram"); "—" when it has none.
	Source    string
	Body      string
	SenderIP  string
	CreatedAt time.Time
}

// AdminMessageFilter narrows the admin message list. A nil GameID/SenderID leaves that
// field unfiltered; NameMask/ExtMask are glob masks (account.LikePattern) matched
// case-insensitively against the sender's display name / any identity's external id.
type AdminMessageFilter struct {
	GameID   uuid.UUID
	SenderID uuid.UUID
	NameMask string
	ExtMask  string
}

// AdminListMessages returns the filtered chat messages — real messages only, nudges
// excluded — newest first, paginated, for the admin moderation console.
func (svc *Service) AdminListMessages(ctx context.Context, f AdminMessageFilter, limit, offset int) ([]AdminMessage, error) {
	return svc.store.adminListMessages(ctx, f, limit, offset)
}

// AdminCountMessages counts the filtered chat messages, for the admin list pager.
func (svc *Service) AdminCountMessages(ctx context.Context, f AdminMessageFilter) (int, error) {
	return svc.store.adminCountMessages(ctx, f)
}

// adminMessageSource is the SQL CASE projecting a sender's source: guest, robot, or its
// oldest identity kind ("—" when it has none).
const adminMessageSource = `CASE
	WHEN a.is_guest THEN 'guest'
	WHEN EXISTS (SELECT 1 FROM backend.identities i WHERE i.account_id = a.account_id AND i.kind = 'robot') THEN 'robot'
	ELSE COALESCE((SELECT i2.kind FROM backend.identities i2 WHERE i2.account_id = a.account_id ORDER BY i2.created_at ASC LIMIT 1), '—')
END`

// adminMessageWhere builds the shared WHERE clause and its positional args (from $1).
// Only real messages are listed; nudges are excluded.
func adminMessageWhere(f AdminMessageFilter) (string, []any) {
	where := `m.kind = 'message'`
	var args []any
	if f.GameID != uuid.Nil {
		args = append(args, f.GameID)
		where += fmt.Sprintf(` AND m.game_id = $%d`, len(args))
	}
	if f.SenderID != uuid.Nil {
		args = append(args, f.SenderID)
		where += fmt.Sprintf(` AND m.sender_id = $%d`, len(args))
	}
	if name := account.LikePattern(f.NameMask); name != "" {
		args = append(args, name)
		where += fmt.Sprintf(` AND a.display_name ILIKE $%d ESCAPE '\'`, len(args))
	}
	if ext := account.LikePattern(f.ExtMask); ext != "" {
		args = append(args, ext)
		where += fmt.Sprintf(` AND EXISTS (SELECT 1 FROM backend.identities ie WHERE ie.account_id = a.account_id AND ie.external_id ILIKE $%d ESCAPE '\')`, len(args))
	}
	return where, args
}

func (s *Store) adminListMessages(ctx context.Context, f AdminMessageFilter, limit, offset int) ([]AdminMessage, error) {
	where, args := adminMessageWhere(f)
	q := `SELECT m.message_id, m.game_id, m.sender_id, a.display_name, ` + adminMessageSource + ` AS source, m.body, COALESCE(m.sender_ip, ''), m.created_at
FROM backend.chat_messages m
JOIN backend.accounts a ON a.account_id = m.sender_id
WHERE ` + where +
		fmt.Sprintf(` ORDER BY m.created_at DESC LIMIT $%d OFFSET $%d`, len(args)+1, len(args)+2)
	args = append(args, limit, offset)
	rows, err := s.db.QueryContext(ctx, q, args...)
	if err != nil {
		return nil, fmt.Errorf("social: admin list messages: %w", err)
	}
	defer rows.Close()
	var out []AdminMessage
	for rows.Next() {
		var m AdminMessage
		if err := rows.Scan(&m.ID, &m.GameID, &m.SenderID, &m.SenderName, &m.Source, &m.Body, &m.SenderIP, &m.CreatedAt); err != nil {
			return nil, fmt.Errorf("social: scan admin message: %w", err)
		}
		out = append(out, m)
	}
	return out, rows.Err()
}

func (s *Store) adminCountMessages(ctx context.Context, f AdminMessageFilter) (int, error) {
	where, args := adminMessageWhere(f)
	var n int
	q := `SELECT COUNT(*) FROM backend.chat_messages m JOIN backend.accounts a ON a.account_id = m.sender_id WHERE ` + where
	if err := s.db.QueryRowContext(ctx, q, args...).Scan(&n); err != nil {
		return 0, fmt.Errorf("social: admin count messages: %w", err)
	}
	return n, nil
}