package handlers

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

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

	"git.eeqj.de/sneak/upaas/internal/database"
	"git.eeqj.de/sneak/upaas/internal/models"
)

// apiTokenResponse is the JSON representation of an API token.
type apiTokenResponse struct {
	ID         string  `json:"id"`
	Name       string  `json:"name"`
	CreatedAt  string  `json:"createdAt"`
	ExpiresAt  *string `json:"expiresAt,omitempty"`
	LastUsedAt *string `json:"lastUsedAt,omitempty"`
}

// apiTokenCreateResponse includes the plaintext token (shown once).
type apiTokenCreateResponse struct {
	apiTokenResponse

	Token string `json:"token"`
}

func tokenToAPI(t *models.APIToken) apiTokenResponse {
	resp := apiTokenResponse{
		ID:        t.ID,
		Name:      t.Name,
		CreatedAt: t.CreatedAt.Format("2006-01-02T15:04:05Z"),
	}

	if t.ExpiresAt.Valid {
		s := t.ExpiresAt.Time.Format("2006-01-02T15:04:05Z")
		resp.ExpiresAt = &s
	}

	if t.LastUsedAt.Valid {
		s := t.LastUsedAt.Time.Format("2006-01-02T15:04:05Z")
		resp.LastUsedAt = &s
	}

	return resp
}

// createTokenRequest is the JSON body for token creation.
type createTokenRequest struct {
	Name string `json:"name"`
}

// createAndSaveToken generates a token, saves it, and returns
// the plaintext and model.
func (h *Handlers) createAndSaveToken(
	ctx context.Context,
	userID int64,
	name string,
) (string, *models.APIToken, error) {
	plaintext, err := models.GenerateToken()
	if err != nil {
		return "", nil, fmt.Errorf("generating: %w", err)
	}

	token := models.NewAPIToken(h.db)
	token.UserID = userID
	token.Name = name
	token.TokenHash = database.HashAPIToken(plaintext)

	saveErr := token.Save(ctx)
	if saveErr != nil {
		return "", nil, fmt.Errorf("saving: %w", saveErr)
	}

	return plaintext, token, nil
}

// HandleAPICreateToken returns a handler that creates an API token.
func (h *Handlers) HandleAPICreateToken() http.HandlerFunc {
	return func(writer http.ResponseWriter, request *http.Request) {
		user, err := h.auth.GetCurrentUser(
			request.Context(), request,
		)
		if err != nil || user == nil {
			h.respondJSON(writer, request,
				map[string]string{"error": "unauthorized"},
				http.StatusUnauthorized)

			return
		}

		var req createTokenRequest

		decodeErr := json.NewDecoder(request.Body).Decode(&req)
		if decodeErr != nil {
			h.respondJSON(writer, request,
				map[string]string{"error": "invalid JSON body"},
				http.StatusBadRequest)

			return
		}

		if req.Name == "" {
			h.respondJSON(writer, request,
				map[string]string{"error": "name is required"},
				http.StatusBadRequest)

			return
		}

		plaintext, token, createErr := h.createAndSaveToken(
			request.Context(), user.ID, req.Name,
		)
		if createErr != nil {
			h.log.Error("api: token creation failed",
				"error", createErr)
			h.respondJSON(writer, request,
				map[string]string{"error": "internal error"},
				http.StatusInternalServerError)

			return
		}

		h.respondJSON(writer, request, apiTokenCreateResponse{
			apiTokenResponse: tokenToAPI(token),
			Token:            plaintext,
		}, http.StatusCreated)
	}
}

// HandleAPIListTokens returns a handler that lists API tokens.
func (h *Handlers) HandleAPIListTokens() http.HandlerFunc {
	return func(writer http.ResponseWriter, request *http.Request) {
		user, err := h.auth.GetCurrentUser(
			request.Context(), request,
		)
		if err != nil || user == nil {
			h.respondJSON(writer, request,
				map[string]string{"error": "unauthorized"},
				http.StatusUnauthorized)

			return
		}

		tokens, listErr := models.ListAPITokensByUser(
			request.Context(), h.db, user.ID,
		)
		if listErr != nil {
			h.log.Error("api: failed to list tokens",
				"error", listErr)
			h.respondJSON(writer, request,
				map[string]string{"error": "internal error"},
				http.StatusInternalServerError)

			return
		}

		result := make([]apiTokenResponse, 0, len(tokens))
		for _, t := range tokens {
			result = append(result, tokenToAPI(t))
		}

		h.respondJSON(writer, request, result, http.StatusOK)
	}
}

// HandleAPIDeleteToken returns a handler that revokes an API token.
func (h *Handlers) HandleAPIDeleteToken() http.HandlerFunc {
	return func(writer http.ResponseWriter, request *http.Request) {
		user, err := h.auth.GetCurrentUser(
			request.Context(), request,
		)
		if err != nil || user == nil {
			h.respondJSON(writer, request,
				map[string]string{"error": "unauthorized"},
				http.StatusUnauthorized)

			return
		}

		tokenID := chi.URLParam(request, "tokenID")

		token, findErr := models.FindAPIToken(
			request.Context(), h.db, tokenID,
		)
		if findErr != nil {
			h.respondJSON(writer, request,
				map[string]string{"error": "internal error"},
				http.StatusInternalServerError)

			return
		}

		if token == nil || token.UserID != user.ID {
			h.respondJSON(writer, request,
				map[string]string{"error": "token not found"},
				http.StatusNotFound)

			return
		}

		deleteErr := token.Delete(request.Context())
		if deleteErr != nil {
			h.log.Error("api: failed to delete token",
				"error", deleteErr)
			h.respondJSON(writer, request,
				map[string]string{"error": "internal error"},
				http.StatusInternalServerError)

			return
		}

		h.respondJSON(writer, request,
			map[string]string{"status": "deleted"},
			http.StatusOK)
	}
}