import type Database from "bun:sqlite";

import { generateText } from "ai";

import type { MaterialType } from "../../shared/api";
import type { Logger } from "../logger";

import { and, asc, eq } from "drizzle-orm";

import { buildProviderRegistry } from "../ai/registry";
import { notDeleted, timestamp, wrap } from "../db/connection";
import { listEntityNames } from "../db/entities";
import { getModelWithProvider, listModels } from "../db/models";
import { materials } from "../db/schema";
import { getSettings } from "../db/settings";

import { getTemplate } from "./templates";

const MAX_RETRIES = 3;
const DEFAULT_INTERVAL_MS = 5000;

export interface ProcessableMaterial {
  description: string;
  id: string;
  materialType: MaterialType;
  projectId: string;
}

export class MaterialProcessor {
  private readonly db: Database;
  private readonly logger: Logger;
  private timer: ReturnType<typeof setInterval> | null = null;
  private running = false;

  constructor(db: Database, logger: Logger) {
    this.db = db;
    this.logger = logger.child({ component: "material-processor" });
  }

  recoverStuckMaterials(): number {
    const db = wrap(this.db);
    const now = timestamp();
    const restored = db
      .update(materials)
      .set({ status: "pending", updatedAt: now })
      .where(and(eq(materials.status, "processing"), notDeleted(materials)))
      .returning({ id: materials.id })
      .all();

    const count = restored.length;
    if (count > 0) {
      this.logger.info({ count }, "恢复卡住的素材到 pending 状态");
    }
    return count;
  }

  start(intervalMs: number = DEFAULT_INTERVAL_MS): void {
    const recovered = this.recoverStuckMaterials();
    this.logger.info({ intervalMs, recovered }, "素材处理器启动");
    this.timer = setInterval(() => {
      void this.tick();
    }, intervalMs);
  }

  stop(): void {
    if (this.timer !== null) {
      clearInterval(this.timer);
      this.timer = null;
    }
    this.running = false;
    this.logger.info("素材处理器停止");
  }

  private async tick(): Promise<void> {
    if (this.running) {
      this.logger.debug("上一轮处理尚未完成，跳过本次扫描");
      return;
    }
    this.running = true;
    try {
      await this.processNext();
    } catch (error: unknown) {
      this.logger.error({ error: error instanceof Error ? error.message : String(error) }, "处理过程中发生未捕获错误");
    } finally {
      this.running = false;
    }
  }

  async processNext(): Promise<void> {
    const db = wrap(this.db);
    const row = db
      .select()
      .from(materials)
      .where(and(eq(materials.status, "pending"), notDeleted(materials)))
      .orderBy(asc(materials.createdAt))
      .limit(1)
      .get();

    if (!row) {
      this.logger.debug("无待处理素材");
      return;
    }

    const processingAt = timestamp();
    db.update(materials).set({ status: "processing", updatedAt: processingAt }).where(eq(materials.id, row.id)).run();

    const material: ProcessableMaterial = {
      description: row.description,
      id: row.id,
      materialType: row.materialType as MaterialType,
      projectId: row.projectId,
    };

    let lastError: unknown;
    let success = false;

    for (let attempt = 1; attempt <= MAX_RETRIES; attempt++) {
      try {
        const result = await this.processOne(material);
        const finishedAt = timestamp();
        db.update(materials)
          .set({ processedContent: result, status: "review", updatedAt: finishedAt })
          .where(eq(materials.id, row.id))
          .run();
        this.logger.info({ attempt, materialId: row.id }, "素材处理成功");
        success = true;
        break;
      } catch (error: unknown) {
        lastError = error;
        this.logger.warn(
          {
            attempt,
            error: error instanceof Error ? error.message : String(error),
            materialId: row.id,
          },
          `素材处理第 ${attempt} 次失败`,
        );
      }
    }

    if (!success) {
      const failedAt = timestamp();
      db.update(materials).set({ status: "failed", updatedAt: failedAt }).where(eq(materials.id, row.id)).run();
      this.logger.warn(
        {
          error: lastError instanceof Error ? lastError.message : String(lastError),
          materialId: row.id,
        },
        `素材处理 ${MAX_RETRIES} 次均失败，标记为 failed`,
      );
    }
  }

  protected async processOne(material: ProcessableMaterial): Promise<string> {
    const modelInfo = getDefaultTextModel(this.db);
    if (!modelInfo) {
      throw new Error("没有可用的文本模型，请在设置中配置默认模型或添加至少一个模型");
    }

    const registry = buildProviderRegistry(this.db);
    const model = registry.languageModel(`${modelInfo.providerId}:${modelInfo.externalId}`);
    const existingEntities = listEntityNames(this.db, material.projectId);
    const template = getTemplate(material.materialType);
    const userPrompt = template.buildUserPrompt(material.description, existingEntities);

    const result = await generateText({
      model,
      prompt: userPrompt,
      system: template.systemPrompt,
    });

    const processingResult = template.parseOutput(result.text);
    return JSON.stringify(processingResult);
  }
}

function getDefaultTextModel(db: Database): { externalId: string; providerId: string } | null {
  try {
    const settings = getSettings(db);
    if (settings.defaultModels?.text) {
      const result = getModelWithProvider(db, settings.defaultModels.text);
      if (!("error" in result)) {
        return { externalId: result.model.externalId, providerId: result.provider.id };
      }
    }
  } catch {
    // settings 不存在或解析失败，使用 fallback
  }

  const fallback = listModels(db, { page: 1, pageSize: 1 });
  const firstModel = fallback.items[0];
  if (!firstModel) return null;

  const result = getModelWithProvider(db, firstModel.id);
  if ("error" in result) return null;

  return { externalId: result.model.externalId, providerId: result.provider.id };
}