package handlers

import (
	"log/slog"
	"net/http"

	"qbank/internal/auth"
	"qbank/internal/db"
	"qbank/internal/models"
)

// QuestionRow pairs a question with its per-user stat for the library display.
type QuestionRow struct {
	Q    *models.Question
	Stat *models.UserQuestionStat // nil = never seen in a test
}

type HomeHandler struct {
	auth   *auth.Manager
	repo   *db.Repo
	render *Renderer
}

func NewHomeHandler(a *auth.Manager, repo *db.Repo, r *Renderer) *HomeHandler {
	return &HomeHandler{auth: a, repo: repo, render: r}
}

func (h *HomeHandler) Handle(w http.ResponseWriter, r *http.Request) {
	user := auth.UserFromCtx(r.Context())

	sortParam := r.URL.Query().Get("sort")
	search := r.URL.Query().Get("q")
	source := r.URL.Query().Get("source")

	var sortOrder db.SortOrder
	switch sortParam {
	case "weakest":
		sortOrder = db.SortWeakest
	case "seen":
		sortOrder = db.SortMostSeen
	default:
		sortParam = "alpha"
		sortOrder = db.SortAlpha
	}

	questions, err := h.repo.ListQuestions(db.ListFilter{
		Source: source,
		Search: search,
		Sort:   sortOrder,
		UserID: user.ID,
	})
	if err != nil {
		slog.Error("list questions", "err", err)
		HTTPError(w, http.StatusInternalServerError)
		return
	}

	ids := make([]string, len(questions))
	for i, q := range questions {
		ids[i] = q.ID
	}

	stats, err := h.repo.GetStatsForUser(user.ID, ids)
	if err != nil {
		slog.Error("get stats", "err", err)
		HTTPError(w, http.StatusInternalServerError)
		return
	}

	rows := make([]QuestionRow, len(questions))
	for i, q := range questions {
		rows[i] = QuestionRow{Q: q, Stat: stats[q.ID]}
	}

	totalQ, _ := h.repo.CountQuestions()
	totalA, _ := h.repo.CountAnswers()
	sourceCounts, _ := h.repo.CountBySource()

	data := BaseData(h.auth, r)
	data["Questions"] = rows
	data["TotalQ"] = totalQ
	data["TotalA"] = totalA
	data["SourceStats"] = sourceCounts
	data["Sort"] = sortParam
	data["Search"] = search
	data["SelectedSource"] = source

	h.render.Render(w, http.StatusOK, "home", data)
}