package oci

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"

	"git.wntrmute.dev/kyle/mcr/internal/policy"
)

type catalogResponse struct {
	Repositories []string `json:"repositories"`
}

func (h *Handler) handleCatalog(w http.ResponseWriter, r *http.Request) {
	if !h.checkPolicy(w, r, policy.ActionCatalog, "") {
		return
	}

	n := 0
	var err error
	if nStr := r.URL.Query().Get("n"); nStr != "" {
		n, err = strconv.Atoi(nStr)
		if err != nil || n < 0 {
			writeOCIError(w, "INVALID_PARAMETER", http.StatusBadRequest, "invalid 'n' parameter")
			return
		}
	}
	last := r.URL.Query().Get("last")

	if n == 0 {
		repos, err := h.db.ListRepositoryNames(last, 10000)
		if err != nil {
			h.log.Error("catalog: list repository names", "error", err)
			writeOCIError(w, "UNKNOWN", http.StatusInternalServerError, "internal error")
			return
		}
		if repos == nil {
			repos = []string{}
		}
		w.Header().Set("Content-Type", "application/json")
		_ = json.NewEncoder(w).Encode(catalogResponse{Repositories: repos})
		return
	}

	repos, err := h.db.ListRepositoryNames(last, n+1)
	if err != nil {
		h.log.Error("catalog: list repository names (paginated)", "error", err)
		writeOCIError(w, "UNKNOWN", http.StatusInternalServerError, "internal error")
		return
	}
	if repos == nil {
		repos = []string{}
	}

	hasMore := len(repos) > n
	if hasMore {
		repos = repos[:n]
	}

	if hasMore {
		lastRepo := repos[len(repos)-1]
		linkURL := fmt.Sprintf("/v2/_catalog?n=%d&last=%s", n, lastRepo)
		w.Header().Set("Link", fmt.Sprintf(`<%s>; rel="next"`, linkURL))
	}

	w.Header().Set("Content-Type", "application/json")
	_ = json.NewEncoder(w).Encode(catalogResponse{Repositories: repos})
}