package handlers

import (
	"encoding/json"
	"io"
	"net/http"

	"git.gophernest.net/azpect/ResumeLens/internal/models"
	"git.gophernest.net/azpect/ResumeLens/internal/services"
)

var analyzeResume = func(resume io.Reader, jobDescription string) (*models.AnalysisResult, error) {
	return services.AnalyzeResume(resume, jobDescription)
}

func SetAnalyzeResumeForTesting(fn func(io.Reader, string) (*models.AnalysisResult, error)) func() {
	prev := analyzeResume
	analyzeResume = fn
	return func() {
		analyzeResume = prev
	}
}

// Analyze handles POST /api/analyze.
// It expects a multipart form with:
//   - "resume"           — the uploaded resume file (PDF)
//   - "job_description"  — the job description as plain text
//
// Trace: SDD_LLD_0005 - Provide HTTP handler and endpoint for multipart/form data uploads
// Trace: SDD_HLD_0001 - Accept PDF resume input
// Trace: SDD_HLD_0004 - Accept job description in textbox
func Analyze(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, 10<<20)

	// Trace: SDD_LLD_0005 - Accept multipart/form data uploads from frontend
	if err := r.ParseMultipartForm(10 << 20); err != nil {
		http.Error(w, "failed to parse form", http.StatusBadRequest)
		return
	}

	// Trace: SDD_HLD_0001 - Accept PDF resume input
	file, _, err := r.FormFile("resume")
	if err != nil {
		http.Error(w, "missing resume file", http.StatusBadRequest)
		return
	}
	defer file.Close()

	// Trace: SDD_HLD_0004 - Read string of text from textbox
	// Trace: SDD_LLD_0021 - Accept textual job description input
	jobDescription := r.FormValue("job_description")
	if jobDescription == "" {
		http.Error(w, "missing job_description", http.StatusBadRequest)
		return
	}

	// Trace: SDD_HLD_0005 - Provide structured inputs to AI grader
	result, err := analyzeResume(file, jobDescription)
	if err != nil {
		// Trace: SDD_LLD_0013 - Handle API failures and error responses
		http.Error(w, "analysis failed: "+err.Error(), http.StatusInternalServerError)
		return
	}

	// Trace: SDD_LLD_0019 - Support JSON output
	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(result)
}