(ns frq.store
  "The one thing worth keeping between runs: the durable broker token.

  It is a credential — anyone holding it can mint session tokens for the
  account — so it lives in the user's config directory with the permissions of
  an ssh key, and never anywhere else. The web-token beside it is single-use
  and deliberately not saved."
  (:require [clojure.edn :as edn]
            [clojure.string :as str]
            [jolt.host :as host]))

(defn config-dir []
  (let [xdg (host/getenv "XDG_CONFIG_HOME")
        home (host/getenv "HOME")]
    (str (if (seq xdg) xdg (str home "/.config")) "/frq")))

(defn session-file [] (str (config-dir) "/session.edn"))

(defn load-session
  "The saved session, or nil. A file that will not parse is treated as absent —
  a stale credential is not worth an error at startup."
  []
  (let [path (session-file)]
    (when (host/file-exists? path)
      (try
        (let [m (edn/read-string (slurp path))]
          (when (and (map? m) (seq (:broker-token m))) m))
        (catch Exception _ nil)))))

(defn save-session!
  "Write {:broker-token :handle :did :nick}, readable by nobody else."
  [session]
  (let [dir (config-dir)
        path (session-file)]
    (try
      (host/mkdirs! dir)
      ;; Created before it is written, so the token is never on disk
      ;; world-readable even for an instant.
      (host/sh (str "install -m 600 /dev/null '" path "'"))
      (spit path (pr-str (select-keys session [:broker-token :handle :did :nick])))
      (host/sh (str "chmod 600 '" path "'"))
      true
      (catch Exception _ false))))

(defn channels-file [] (str (config-dir) "/channels.edn"))

(defn load-channels
  "The channels this client has opened, in the order it last used them. Unlike
  the session beside it this is not a credential — just names — so it is an
  ordinary file."
  []
  (let [path (channels-file)]
    (when (host/file-exists? path)
      (try
        (let [v (edn/read-string (slurp path))]
          (when (vector? v) (filterv string? v)))
        (catch Exception _ nil)))))

(defn save-channels!
  "Write the channel names, most recently used first."
  [names]
  (try
    (host/mkdirs! (config-dir))
    (spit (channels-file) (pr-str (vec names)))
    true
    (catch Exception _ false)))

(defn clear-session! []
  (try
    (when (host/file-exists? (session-file))
      (host/delete-file! (session-file)))
    true
    (catch Exception _ false)))