import OpenAI from "openai";
import { zodTextFormat } from "openai/helpers/zod";

import { competitorAnalysisSchema, type CompetitorAnalysis, type SectorRequest } from "@/lib/schema";

const DEFAULT_OPENAI_MODEL = "gpt-5.4-mini";

let cachedClient: OpenAI | null = null;

function getOpenAIClient() {
  const apiKey = process.env.OPENAI_API_KEY;

  if (!apiKey) {
    throw new Error("Missing OPENAI_API_KEY environment variable.");
  }

  cachedClient ??= new OpenAI({ apiKey });

  return cachedClient;
}

function buildPrompt(request: SectorRequest) {
  const context = [
    `Sector: ${request.sector}`,
    request.geography ? `Geography: ${request.geography}` : null,
    request.customerType ? `Customer type: ${request.customerType}` : null,
    request.focus ? `Strategic focus: ${request.focus}` : null
  ]
    .filter(Boolean)
    .join("\n");

  return `${context}

Produce a competitive landscape analysis from the perspective of a new market entrant.
Keep the output grounded, specific, and commercially useful.
Do not include markdown, preamble, or citations in the JSON fields.
Make sure there are 4 to 6 key players, 3 to 5 emerging trends, and 2 to 3 white-space opportunities.
Always include at least 2 concrete uncertainties in data_confidence.flagged_uncertainties.`;
}

export async function generateCompetitorAnalysis(
  request: SectorRequest
): Promise<CompetitorAnalysis> {
  const client = getOpenAIClient();
  const model = process.env.OPENAI_MODEL || DEFAULT_OPENAI_MODEL;

  const response = await client.responses.parse({
    model,
    reasoning: {
      effort: "medium"
    },
    max_output_tokens: 2200,
    instructions:
      "You are an AI-powered competitive intelligence engine for early-stage startups. Return only content that matches the requested schema. Keep each field concise and decision-useful for a new entrant.",
    input: buildPrompt(request),
    text: {
      format: zodTextFormat(competitorAnalysisSchema, "competitor_analysis"),
      verbosity: "medium"
    }
  });

  if (!response.output_parsed) {
    throw new Error("OpenAI returned no structured analysis payload.");
  }

  return competitorAnalysisSchema.parse(response.output_parsed);
}