package shareapi

import (
	"context"
	"encoding/json"
	"errors"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/itworx/pulse/internal/auth"
	"github.com/itworx/pulse/internal/problem"
	"github.com/itworx/pulse/internal/share"
)

type Handler struct {
	Provider    share.Provider
	MaxPageSize int
}

func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet || (r.URL.Path != "/api/v1/shares" && !strings.HasPrefix(r.URL.Path, "/api/v1/shares/")) {
		http.NotFound(w, r)
		return
	}
	if _, ok := auth.PrincipalFromContext(r.Context()); !ok {
		problem.Write(w, r, http.StatusUnauthorized, "UNAUTHORIZED", "Authentication required", "Authentication is required to read shares.", nil)
		return
	}
	if err := r.Context().Err(); err != nil {
		return
	}
	snapshot, err := h.snapshot(r)
	if err != nil {
		if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
			return
		}
		problem.Write(w, r, http.StatusServiceUnavailable, "SHARES_UNAVAILABLE", "Sharegegevens niet beschikbaar", "De sharegegevens konden niet worden gelezen.", nil)
		return
	}
	if strings.HasPrefix(r.URL.Path, "/api/v1/shares/") {
		id := strings.TrimPrefix(r.URL.Path, "/api/v1/shares/")
		item, ok := share.ShareByID(snapshot, id)
		if !ok {
			http.NotFound(w, r)
			return
		}
		writeJSON(w, struct {
			Source share.Source `json:"source"`
			Share  share.Share  `json:"share"`
		}{snapshot.Source, item})
		return
	}
	limit := 50
	if value := r.URL.Query().Get("limit"); value != "" {
		parsed, parseErr := strconv.Atoi(value)
		if parseErr != nil {
			problem.Write(w, r, http.StatusBadRequest, "SHARE_QUERY_INVALID", "Invalid share query", "De sharelimiet is ongeldig.", nil)
			return
		}
		limit = parsed
	}
	max := h.MaxPageSize
	if max == 0 {
		max = 100
	}
	if limit < 1 || limit > max {
		problem.Write(w, r, http.StatusBadRequest, "SHARE_QUERY_INVALID", "Invalid share query", "De sharelimiet is ongeldig.", nil)
		return
	}
	if limit < len(snapshot.Shares) {
		snapshot.Shares = snapshot.Shares[:limit]
	}
	writeJSON(w, snapshot)
}
func (h Handler) snapshot(r *http.Request) (share.Snapshot, error) {
	if h.Provider == nil {
		return share.UnknownSnapshot(time.Now().UTC(), "shares", "unraid", "source_unavailable"), nil
	}
	return h.Provider.Snapshot(r.Context())
}
func writeJSON(w http.ResponseWriter, value any) {
	w.Header().Set("Content-Type", "application/json")
	w.Header().Set("Cache-Control", "private, max-age=5")
	_ = json.NewEncoder(w).Encode(value)
}