import cron from "node-cron";
import type { Event } from "./event-queue.js";
import { logger } from "./logger.js";

export interface CronJob {
  name: string;
  expression: string;
  instruction: string;
}

type EnqueueFn = (event: Omit<Event, "id" | "timestamp">) => Event | null;

export class CronScheduler {
  private tasks: Map<string, cron.ScheduledTask> = new Map();

  parseConfig(content: string): CronJob[] {
    const jobs: CronJob[] = [];
    const lines = content.split("\n");

    // Find the "## Cron Jobs" section
    let inCronSection = false;
    let currentName: string | null = null;
    let currentExpression: string | null = null;
    let currentInstruction: string | null = null;

    for (const line of lines) {
      // Detect start of "## Cron Jobs" section
      const h2Match = line.match(/^##\s+(.+)$/);
      if (h2Match) {
        if (inCronSection) {
          // We hit another ## heading — check if it's a ### job or end of section
          // A ## heading ends the Cron Jobs section
          if (currentName !== null && currentExpression !== null && currentInstruction !== null) {
            jobs.push({ name: currentName, expression: currentExpression, instruction: currentInstruction });
          }
          currentName = null;
          currentExpression = null;
          currentInstruction = null;
          inCronSection = false;
        }
        if (h2Match[1].trim() === "Cron Jobs") {
          inCronSection = true;
        }
        continue;
      }

      if (!inCronSection) continue;

      // Detect ### job name headers within the Cron Jobs section
      const h3Match = line.match(/^###\s+(.+)$/);
      if (h3Match) {
        // Push previous job if complete
        if (currentName !== null && currentExpression !== null && currentInstruction !== null) {
          jobs.push({ name: currentName, expression: currentExpression, instruction: currentInstruction });
        }
        currentName = h3Match[1].trim();
        currentExpression = null;
        currentInstruction = null;
        continue;
      }

      const cronMatch = line.match(/^Cron:\s*(.+)$/);
      if (cronMatch && currentName !== null) {
        currentExpression = cronMatch[1].trim();
        continue;
      }

      const instructionMatch = line.match(/^Instruction:\s*(.+)$/);
      if (instructionMatch && currentName !== null) {
        currentInstruction = instructionMatch[1].trim();
        continue;
      }
    }

    // Push the last job if complete
    if (inCronSection && currentName !== null && currentExpression !== null && currentInstruction !== null) {
      jobs.push({ name: currentName, expression: currentExpression, instruction: currentInstruction });
    }

    return jobs;
  }

  start(jobs: CronJob[], enqueue: EnqueueFn): void {
    for (const job of jobs) {
      if (!cron.validate(job.expression)) {
        logger.warn({ name: job.name, expression: job.expression }, "Cron job has invalid cron expression, skipping");
        continue;
      }

      const task = cron.schedule(job.expression, () => {
        enqueue({
          type: "cron",
          payload: {
            instruction: job.instruction,
            jobName: job.name,
          },
          source: "cron-scheduler",
        });
      });

      this.tasks.set(job.name, task);
    }
  }

  stop(): void {
    for (const task of this.tasks.values()) {
      task.stop();
    }
    this.tasks.clear();
  }
}