API Go pour convertir LaTeX en PDF

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"os"
)

const (
	apiKey = "your-api-key" // use os.Getenv in production
	apiURL = "https://api.formatex.io/api/v1"
)

func main() {
	latex := `\documentclass{article}
\usepackage{amsmath}
\begin{document}
Hello from Go! $E = mc^2$
\end{document}`

	pdf, err := compileLaTeX(latex, "pdflatex")
	if err != nil {
		fmt.Fprintf(os.Stderr, "error: %v\n", err)
		os.Exit(1)
	}

	if err := os.WriteFile("output.pdf", pdf, 0644); err != nil {
		fmt.Fprintf(os.Stderr, "write error: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("PDF saved to output.pdf")
}

func compileLaTeX(source, engine string) ([]byte, error) {
	body, _ := json.Marshal(map[string]string{
		"latex": source,
		"engine": engine,
	})

	req, _ := http.NewRequest("POST", apiURL+"/compile", bytes.NewReader(body))
	req.Header.Set("X-API-Key", apiKey)
	req.Header.Set("Content-Type", "application/json")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		errBody, _ := io.ReadAll(resp.Body)
		return nil, fmt.Errorf("API error %d: %s", resp.StatusCode, errBody)
	}

	return io.ReadAll(resp.Body)
}

package main

import (
	"bytes"
	"encoding/json"
	"io"
	"net/http"
	"os"
)

func generatePDFHandler(w http.ResponseWriter, r *http.Request) {
	var req struct {
		Source string `json:"source"`
		Engine string `json:"engine"`
	}
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "invalid request", http.StatusBadRequest)
		return
	}
	if req.Engine == "" {
		req.Engine = "pdflatex"
	}

	body, _ := json.Marshal(map[string]string{
		"latex":  req.Source,
		"engine": req.Engine,
	})
	apiReq, _ := http.NewRequest("POST",
		"https://api.formatex.io/api/v1/compile",
		bytes.NewReader(body),
	)
	apiReq.Header.Set("X-API-Key", os.Getenv("FORMATEX_API_KEY"))
	apiReq.Header.Set("Content-Type", "application/json")

	resp, err := http.DefaultClient.Do(apiReq)
	if err != nil {
		http.Error(w, "upstream error", http.StatusBadGateway)
		return
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		w.WriteHeader(http.StatusInternalServerError)
		io.Copy(w, resp.Body)
		return
	}

	w.Header().Set("Content-Type", "application/pdf")
	w.Header().Set("Content-Disposition", "attachment; filename=output.pdf")
	io.Copy(w, resp.Body)
}