import { dbGlobal } from "drizzle-pkg/lib/db";
import { characterSessions, characterMessages } from "drizzle-pkg/lib/schema/character";
import { eq, desc, asc, and, isNull, sql, max } from "drizzle-orm";
import type { CharacterSessionRow, CharacterMessageRow } from "./types";

export async function createCharacterSession(params: {
  userId?: number | null;
  tempToken?: string | null;
  cardId?: number | null;
  modelId?: number | null;
  expiresAt?: Date | null;
}): Promise<CharacterSessionRow> {
  const id = `cs_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 10)}`;
  const [row] = await dbGlobal
    .insert(characterSessions)
    .values({
      id,
      userId: params.userId ?? null,
      tempToken: params.tempToken ?? null,
      cardId: params.cardId ?? null,
      modelId: params.modelId ?? null,
      expiresAt: params.expiresAt ?? null,
    })
    .returning();
  return row!;
}

export async function getCharacterSessionById(id: string): Promise<CharacterSessionRow | null> {
  const [row] = await dbGlobal
    .select()
    .from(characterSessions)
    .where(and(eq(characterSessions.id, id), isNull(characterSessions.deletedAt)))
    .limit(1);
  return row ?? null;
}

export async function getCharacterSessionByIdAndUser(
  id: string,
  userId: number | null,
  tempToken: string | null,
): Promise<CharacterSessionRow | null> {
  const conditions = [eq(characterSessions.id, id), isNull(characterSessions.deletedAt)];
  if (userId) {
    conditions.push(eq(characterSessions.userId, userId));
  } else if (tempToken) {
    conditions.push(eq(characterSessions.tempToken, tempToken));
  } else {
    return null;
  }
  const [row] = await dbGlobal
    .select()
    .from(characterSessions)
    .where(and(...conditions))
    .limit(1);
  return row ?? null;
}

export async function listCharacterSessions(params: {
  userId?: number | null;
  tempToken?: string | null;
  cardId?: number | null;
  page?: number;
  pageSize?: number;
}): Promise<{ list: CharacterSessionRow[]; total: number; page: number; pageSize: number; totalPages: number }> {
  const { page = 1, pageSize = 30 } = params;
  const conditions = [isNull(characterSessions.deletedAt)];
  if (params.userId) {
    conditions.push(eq(characterSessions.userId, params.userId));
  } else if (params.tempToken) {
    conditions.push(eq(characterSessions.tempToken, params.tempToken));
  } else {
    return { list: [], total: 0, page, pageSize, totalPages: 0 };
  }
  if (params.cardId) {
    conditions.push(eq(characterSessions.cardId, params.cardId));
  }

  const where = and(...conditions);

  const [countResult] = await dbGlobal
    .select({ count: sql<number>`count(*)` })
    .from(characterSessions)
    .where(where);
  const total = countResult?.count ?? 0;
  const totalPages = Math.ceil(total / pageSize);

  const list = await dbGlobal
    .select()
    .from(characterSessions)
    .where(where)
    .orderBy(desc(characterSessions.lastActiveAt))
    .limit(pageSize)
    .offset((page - 1) * pageSize);

  return { list, total, page, pageSize, totalPages };
}

export async function updateCharacterSession(
  id: string,
  data: {
    title?: string;
    cardId?: number | null;
    modelId?: number | null;
    lastActiveAt?: Date;
  },
): Promise<void> {
  const updates: Record<string, any> = {};
  if (data.title !== undefined) updates.title = data.title;
  if (data.cardId !== undefined) updates.cardId = data.cardId;
  if (data.modelId !== undefined) updates.modelId = data.modelId;
  if (data.lastActiveAt !== undefined) updates.lastActiveAt = data.lastActiveAt;
  if (Object.keys(updates).length === 0) return;
  await dbGlobal.update(characterSessions).set(updates).where(eq(characterSessions.id, id));
}

export async function softDeleteCharacterSession(id: string): Promise<void> {
  await dbGlobal
    .update(characterSessions)
    .set({ deletedAt: new Date() })
    .where(eq(characterSessions.id, id));
}

export async function getMessagesByCharacterSession(
  sessionId: string,
  params?: { limit?: number; latest?: boolean },
): Promise<CharacterMessageRow[]> {
  const { limit = 50, latest = false } = params ?? {};
  const baseQuery = () =>
    dbGlobal.select().from(characterMessages).where(eq(characterMessages.sessionId, sessionId));

  if (latest) {
    const rows = await baseQuery().orderBy(desc(characterMessages.sortOrder)).limit(limit);
    return rows.reverse();
  }
  return baseQuery().orderBy(asc(characterMessages.sortOrder)).limit(limit);
}

export async function getMaxCharacterSortOrder(sessionId: string): Promise<number> {
  const [result] = await dbGlobal
    .select({ maxSort: max(characterMessages.sortOrder) })
    .from(characterMessages)
    .where(eq(characterMessages.sessionId, sessionId));
  return result?.maxSort ?? 0;
}

export async function saveCharacterMessage(params: {
  sessionId: string;
  role: string;
  content: string;
  sortOrder: number;
}): Promise<CharacterMessageRow> {
  const id = `cm_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 10)}`;
  const [row] = await dbGlobal
    .insert(characterMessages)
    .values({
      id,
      sessionId: params.sessionId,
      role: params.role,
      content: params.content,
      sortOrder: params.sortOrder,
    })
    .returning();
  return row!;
}

export async function countCharacterMessagesByRole(sessionId: string, role: string): Promise<number> {
  const [result] = await dbGlobal
    .select({ cnt: sql<number>`cast(count(*) as integer)` })
    .from(characterMessages)
    .where(and(eq(characterMessages.sessionId, sessionId), eq(characterMessages.role, role)));
  return result?.cnt ?? 0;
}

export async function touchCharacterSession(sessionId: string): Promise<void> {
  await dbGlobal
    .update(characterSessions)
    .set({ lastActiveAt: new Date() })
    .where(eq(characterSessions.id, sessionId));
}