package httpapi

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

	"tutor/internal/interview"
)

type createDiagnosticSessionRequest struct {
	UserID            string   `json:"user_id"`
	TargetRole        string   `json:"target_role"`
	Stack             []string `json:"stack"`
	InterviewTimeline string   `json:"interview_timeline"`
	Lang              string   `json:"lang"`
}

type submitDiagnosticAnswerRequest struct {
	QuestionID string `json:"question_id"`
	AnswerText string `json:"answer_text"`
}

func (h Handler) createDiagnosticSession(w http.ResponseWriter, r *http.Request) {
	var req createDiagnosticSessionRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid JSON body")
		return
	}

	lang := req.Lang
	if lang == "" {
		lang = r.Header.Get("X-Lang")
	}
	if lang == "" {
		lang = "en"
	}
	session, err := h.diagnostic.CreateSession(r.Context(), interview.CreateSessionInput{
		UserID:            req.UserID,
		TargetRole:        req.TargetRole,
		Stack:             req.Stack,
		InterviewTimeline: req.InterviewTimeline,
		Lang:              lang,
	})
	if err != nil {
		writeError(w, http.StatusBadRequest, err.Error())
		return
	}

	writeJSON(w, http.StatusCreated, session)
}

func (h Handler) getDiagnosticSession(w http.ResponseWriter, r *http.Request) {
	session, err := h.diagnostic.GetSession(r.PathValue("id"))
	if errors.Is(err, interview.ErrSessionNotFound) {
		writeError(w, http.StatusNotFound, "diagnostic session not found")
		return
	}
	if err != nil {
		writeError(w, http.StatusInternalServerError, "could not load diagnostic session")
		return
	}

	writeJSON(w, http.StatusOK, session)
}

func (h Handler) submitDiagnosticAnswer(w http.ResponseWriter, r *http.Request) {
	var req submitDiagnosticAnswerRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid JSON body")
		return
	}

	answer, err := h.diagnostic.SubmitAnswer(r.Context(), interview.SubmitAnswerInput{
		SessionID:  r.PathValue("id"),
		QuestionID: req.QuestionID,
		AnswerText: req.AnswerText,
	})
	if errors.Is(err, interview.ErrSessionNotFound) || errors.Is(err, interview.ErrQuestionNotFound) {
		writeError(w, http.StatusNotFound, err.Error())
		return
	}
	if err != nil {
		writeError(w, http.StatusBadRequest, err.Error())
		return
	}

	writeJSON(w, http.StatusCreated, answer)
}