package api

import (
	"encoding/json"
	"errors"
	"net/http"
	"strings"

	"git.fabledsword.com/bvandeusen/minstrel/internal/apierror"
	"git.fabledsword.com/bvandeusen/minstrel/internal/backup"
)

// GET /api/admin/backups — the backup's verdict, settings and recent runs.
func (h *handlers) handleGetBackups(w http.ResponseWriter, r *http.Request) {
	st, err := h.backups.Status(r.Context())
	if err != nil {
		writeErrWithLog(w, h.logger, "admin backups: status", apierror.Internal(err))
		return
	}
	writeJSON(w, http.StatusOK, st)
}

func decodeBackupUpdate(w http.ResponseWriter, r *http.Request) (backup.Update, bool) {
	var u backup.Update
	if err := json.NewDecoder(r.Body).Decode(&u); err != nil {
		writeErr(w, apierror.BadRequest("invalid_body", ""))
		return u, false
	}
	return u, true
}

// fieldErr writes a setting that can't be kept as a 400 whose message says
// which setting and why, and reports whether err was one.
func fieldErr(w http.ResponseWriter, err error) bool {
	var fe *backup.FieldError
	if !errors.As(err, &fe) {
		return false
	}
	writeErr(w, apierror.BadRequest("invalid_backup_setting", fe.Message))
	return true
}

// PUT /api/admin/backups — save the settings. An empty secret_key keeps the
// stored one. Returns the new status.
func (h *handlers) handleUpdateBackups(w http.ResponseWriter, r *http.Request) {
	u, ok := decodeBackupUpdate(w, r)
	if !ok {
		return
	}
	if err := h.backups.Save(r.Context(), u); err != nil {
		if !fieldErr(w, err) {
			writeErrWithLog(w, h.logger, "admin backups: save", apierror.Internal(err))
		}
		return
	}
	h.handleGetBackups(w, r)
}

// POST /api/admin/backups/test — check the destination in the body without
// saving it, by listing the backups already there. Nothing is written.
func (h *handlers) handleTestBackups(w http.ResponseWriter, r *http.Request) {
	u, ok := decodeBackupUpdate(w, r)
	if !ok {
		return
	}
	res, err := h.backups.Test(r.Context(), u)
	if err != nil {
		if fieldErr(w, err) {
			return
		}
		msg := strings.TrimPrefix(err.Error(), "backup: ")
		writeErr(w, &apierror.Error{Status: http.StatusBadGateway, Code: "destination_failed", Message: msg})
		return
	}
	writeJSON(w, http.StatusOK, res)
}

// POST /api/admin/backups/run — start a backup now. 202 once it has started;
// 409 while one runs or before the destination is set up.
func (h *handlers) handleRunBackup(w http.ResponseWriter, r *http.Request) {
	err := h.backups.Start(r.Context(), backup.TriggerManual)
	switch {
	case err == nil:
		w.WriteHeader(http.StatusAccepted)
	case errors.Is(err, backup.ErrRunning):
		writeErr(w, apierror.Conflict("backup_running", "A backup is already running."))
	case errors.Is(err, backup.ErrNotReady):
		writeErr(w, apierror.Conflict("backup_not_ready", "Set up where backups go first."))
	case errors.Is(err, backup.ErrClosed):
		writeErr(w, apierror.Conflict("shutting_down", "The server is shutting down."))
	default:
		writeErrWithLog(w, h.logger, "admin backups: start", apierror.Internal(err))
	}
}