/**
 * Service for inferring job details from a pasted job description.
 */

import { getSetting } from '../repositories/settings.js';
import type { ManualJobDraft } from '../../shared/types.js';
import { callOpenRouter, type JsonSchemaDefinition } from './openrouter.js';

export interface ManualJobInferenceResult {
  job: ManualJobDraft;
  warning?: string | null;
}

/** Raw response type from the API (all fields are strings) */
interface ManualJobApiResponse {
  title: string;
  employer: string;
  location: string;
  salary: string;
  deadline: string;
  jobUrl: string;
  applicationLink: string;
  jobType: string;
  jobLevel: string;
  jobFunction: string;
  disciplines: string;
  degreeRequired: string;
  starting: string;
}

/** JSON schema for manual job extraction response */
const MANUAL_JOB_SCHEMA: JsonSchemaDefinition = {
  name: 'manual_job_details',
  schema: {
    type: 'object',
    properties: {
      title: { type: 'string', description: 'Job title' },
      employer: { type: 'string', description: 'Company/employer name' },
      location: { type: 'string', description: 'Job location' },
      salary: { type: 'string', description: 'Salary information' },
      deadline: { type: 'string', description: 'Application deadline' },
      jobUrl: { type: 'string', description: 'URL of the job listing' },
      applicationLink: { type: 'string', description: 'Direct application URL' },
      jobType: { type: 'string', description: 'Employment type (full-time, part-time, etc.)' },
      jobLevel: { type: 'string', description: 'Seniority level (entry, mid, senior, etc.)' },
      jobFunction: { type: 'string', description: 'Job function/category' },
      disciplines: { type: 'string', description: 'Required disciplines or fields' },
      degreeRequired: { type: 'string', description: 'Required degree or education' },
      starting: { type: 'string', description: 'Start date information' },
    },
    required: ['title', 'employer', 'location', 'salary', 'deadline', 'jobUrl', 'applicationLink', 'jobType', 'jobLevel', 'jobFunction', 'disciplines', 'degreeRequired', 'starting'],
    additionalProperties: false,
  },
};

export async function inferManualJobDetails(jobDescription: string): Promise<ManualJobInferenceResult> {
  if (!process.env.OPENROUTER_API_KEY) {
    return {
      job: {},
      warning: 'OPENROUTER_API_KEY not set. Fill details manually.',
    };
  }

  const overrideModel = await getSetting('model');
  const model = overrideModel || process.env.MODEL || 'openai/gpt-4o-mini';
  const prompt = buildInferencePrompt(jobDescription);

  const result = await callOpenRouter<ManualJobApiResponse>({
    model,
    messages: [{ role: 'user', content: prompt }],
    jsonSchema: MANUAL_JOB_SCHEMA,
  });

  if (!result.success) {
    console.warn('Manual job inference failed:', result.error);
    return {
      job: {},
      warning: 'AI inference failed. Fill details manually.',
    };
  }

  return { job: normalizeDraft(result.data) };
}

function buildInferencePrompt(jd: string): string {
  return `
You are extracting structured data from a job description.
Return JSON only with the keys listed below. Use empty string if unknown.
Do not guess or invent data.

Keys:
- title
- employer
- location
- salary
- deadline
- jobUrl (the listing URL, if present)
- applicationLink (the apply URL, if present)
- jobType
- jobLevel
- jobFunction
- disciplines
- degreeRequired
- starting

JOB DESCRIPTION:
${jd}

OUTPUT FORMAT (JSON ONLY):
{
  "title": "",
  "employer": "",
  "location": "",
  "salary": "",
  "deadline": "",
  "jobUrl": "",
  "applicationLink": "",
  "jobType": "",
  "jobLevel": "",
  "jobFunction": "",
  "disciplines": "",
  "degreeRequired": "",
  "starting": ""
}
`.trim();
}

function normalizeDraft(parsed: ManualJobApiResponse): ManualJobDraft {
  const out: ManualJobDraft = {};

  // Map each field, only including non-empty strings
  if (parsed.title?.trim()) out.title = parsed.title.trim();
  if (parsed.employer?.trim()) out.employer = parsed.employer.trim();
  if (parsed.location?.trim()) out.location = parsed.location.trim();
  if (parsed.salary?.trim()) out.salary = parsed.salary.trim();
  if (parsed.deadline?.trim()) out.deadline = parsed.deadline.trim();
  if (parsed.jobUrl?.trim()) out.jobUrl = parsed.jobUrl.trim();
  if (parsed.applicationLink?.trim()) out.applicationLink = parsed.applicationLink.trim();
  if (parsed.jobType?.trim()) out.jobType = parsed.jobType.trim();
  if (parsed.jobLevel?.trim()) out.jobLevel = parsed.jobLevel.trim();
  if (parsed.jobFunction?.trim()) out.jobFunction = parsed.jobFunction.trim();
  if (parsed.disciplines?.trim()) out.disciplines = parsed.disciplines.trim();
  if (parsed.degreeRequired?.trim()) out.degreeRequired = parsed.degreeRequired.trim();
  if (parsed.starting?.trim()) out.starting = parsed.starting.trim();

  return out;
}