import { getChatProvider } from '../factory'
import { getSystemConfig } from '@/lib/config'

export class MathFromTextService {
  async generate(description: string): Promise<string> {
    if (!description?.trim()) {
      throw new Error('Description is required')
    }

    const systemPrompt = `You are a mathematician and LaTeX expert.
Convert the user's natural language description into a single valid LaTeX equation.

CRITICAL RULES:
- Output ONLY the raw LaTeX code — no preamble, no explanation, no markdown fence, no \\[ or \\( delimiters.
- Use standard amsmath/amssymb syntax.
- Never output \\documentclass, \\begin{document}, or $$ delimiters.

Examples:
- "the quadratic formula" -> x = \\frac{-b \\pm \\sqrt{b^2 - 4ac}}{2a}
- "Pythagorean theorem" -> a^2 + b^2 = c^2
- "Euler's identity" -> e^{i\\pi} + 1 = 0
- "la dérivée de x au carré" -> \\frac{d}{dx} x^2 = 2x`

    const userPrompt = `Convert this to LaTeX:\n\n${description}`

    const config = await getSystemConfig()
    const provider = getChatProvider(config)
    const fullPrompt = `${systemPrompt}\n\n${userPrompt}`
    const raw = await provider.generateText(fullPrompt)
    return this.extractLatex(raw)
  }

  private extractLatex(response: string): string {
    const codeBlock = response.match(/```(?:latex|tex|math)?\n([\s\S]+?)\n```/)
    if (codeBlock) return codeBlock[1].trim()
    return response
      .replace(/^\\\[|\\\]$/g, '')
      .replace(/^\\\(|\\\)$/g, '')
      .replace(/^\$\$|\$\$$/g, '')
      .trim()
  }
}

export const mathFromTextService = new MathFromTextService()