package handlers

import (
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"net/http"
	"strconv"
	"time"

	"github.com/go-chi/chi/v5"
	"xorm.io/xorm"

	"github.com/forgeo/forgebucket/internal/api/middleware"
	"github.com/forgeo/forgebucket/internal/models"
)

type DeployKeyHandler struct{ db *xorm.Engine }

func NewDeployKeyHandler(db *xorm.Engine) *DeployKeyHandler { return &DeployKeyHandler{db: db} }

// generateToken produces a prefixed random token and its SHA-256 hex hash.
func generateToken(prefix string) (raw, hash string, err error) {
	b := make([]byte, 32)
	if _, err = rand.Read(b); err != nil {
		return
	}
	raw = prefix + base64.RawURLEncoding.EncodeToString(b)
	sum := sha256.Sum256([]byte(raw))
	hash = hex.EncodeToString(sum[:])
	return
}

func sha256Hex(s string) string {
	sum := sha256.Sum256([]byte(s))
	return hex.EncodeToString(sum[:])
}

type deployKeyResponse struct {
	ID        int64  `json:"id"`
	Title     string `json:"title"`
	ReadOnly  bool   `json:"readOnly"`
	CreatedAt string `json:"createdAt"`
	// Token is only populated on creation; empty on subsequent list calls.
	Token string `json:"token,omitempty"`
}

func (h *DeployKeyHandler) lookupRepo(w http.ResponseWriter, r *http.Request) (*models.Repository, *models.User, bool) {
	repo, ok := resolveRepo(h.db, w, r)
	if !ok {
		return nil, nil, false
	}
	var owner models.User
	h.db.ID(repo.OwnerID).Get(&owner)
	return repo, &owner, true
}

func (h *DeployKeyHandler) canManage(repo *models.Repository, callerID int64) bool {
	if callerID == repo.OwnerID {
		return true
	}
	var m models.RepoMember
	found, _ := h.db.Where("repo_id = ? AND user_id = ? AND permission = 'admin'", repo.ID, callerID).Get(&m)
	return found
}

func (h *DeployKeyHandler) List(w http.ResponseWriter, r *http.Request) {
	repo, _, ok := h.lookupRepo(w, r)
	if !ok {
		return
	}
	var keys []models.RepoDeployKey
	h.db.Where("repo_id = ?", repo.ID).OrderBy("created_at desc").Find(&keys)
	resp := make([]deployKeyResponse, 0, len(keys))
	for _, k := range keys {
		resp = append(resp, deployKeyResponse{
			ID:        k.ID,
			Title:     k.Title,
			ReadOnly:  k.ReadOnly,
			CreatedAt: k.CreatedAt.Format(time.RFC3339),
		})
	}
	jsonOK(w, resp)
}

func (h *DeployKeyHandler) Create(w http.ResponseWriter, r *http.Request) {
	repo, _, ok := h.lookupRepo(w, r)
	if !ok {
		return
	}
	callerID, _ := middleware.UserIDFromContext(r.Context())
	if !h.canManage(repo, callerID) {
		jsonError(w, "only the owner or an admin can manage access keys", http.StatusForbidden)
		return
	}

	var body struct {
		Title    string `json:"title"`
		ReadOnly bool   `json:"readOnly"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil || body.Title == "" {
		jsonError(w, "title is required", http.StatusBadRequest)
		return
	}

	raw, hash, err := generateToken("fbdk_")
	if err != nil {
		jsonError(w, "could not generate token", http.StatusInternalServerError)
		return
	}

	key := &models.RepoDeployKey{
		RepoID:    repo.ID,
		Title:     body.Title,
		TokenHash: hash,
		ReadOnly:  body.ReadOnly,
	}
	if _, err := h.db.Insert(key); err != nil {
		jsonError(w, "could not save key", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(deployKeyResponse{
		ID:        key.ID,
		Title:     key.Title,
		ReadOnly:  key.ReadOnly,
		CreatedAt: key.CreatedAt.Format(time.RFC3339),
		Token:     raw,
	})
}

func (h *DeployKeyHandler) Delete(w http.ResponseWriter, r *http.Request) {
	repo, _, ok := h.lookupRepo(w, r)
	if !ok {
		return
	}
	callerID, _ := middleware.UserIDFromContext(r.Context())
	if !h.canManage(repo, callerID) {
		jsonError(w, "only the owner or an admin can manage access keys", http.StatusForbidden)
		return
	}

	keyID, err := strconv.ParseInt(chi.URLParam(r, "keyID"), 10, 64)
	if err != nil {
		jsonError(w, "invalid key ID", http.StatusBadRequest)
		return
	}
	h.db.Where("id = ? AND repo_id = ?", keyID, repo.ID).Delete(&models.RepoDeployKey{})
	w.WriteHeader(http.StatusNoContent)
}

// AuthenticateDeployKey checks if the given raw token is a valid deploy key for the repo.
// Returns (readOnly, ok).
func AuthenticateDeployKey(db *xorm.Engine, repoID int64, rawToken string) (readOnly bool, ok bool) {
	if len(rawToken) < 5 {
		return false, false
	}
	hash := sha256Hex(rawToken)
	var key models.RepoDeployKey
	found, _ := db.Where("repo_id = ? AND token_hash = ?", repoID, hash).Get(&key)
	if !found {
		return false, false
	}
	// Update last_used
	now := time.Now()
	key.LastUsed = &now
	db.ID(key.ID).Cols("last_used_at").Update(&key)
	return key.ReadOnly, true
}