(ns status-im.utils.contenthash

"TODO: currently we only support encoding/decoding ipfs contenthash

(:refer-clojure :exclude [cat])

(:require [alphabase.base58 :as b58]

[alphabase.hex :as hex]

[clojure.string :as string]

[status-im.ethereum.core :as ethereum]

[status-im.ipfs.core :as ipfs]

[status-im.utils.fx :as fx]))

(defn encode [{:keys [hash namespace ipld]}]

(when (and hash

(= namespace :ipfs)

(nil? ipld))

(when-let [b58-hash (if (string/starts-with? hash "z")

(when (= (count hash) 49)

;; this is a CID multihash

;; the z is removed, it indicates that the

;; CID is b58 encoded

(subs hash 1))

(when (= (count hash) 46)

;; this is a deprecated simple ipfs hash

hash))]

(str "0xe301" (hex/encode (b58/decode b58-hash))))))

(defn decode

"TODO properly decode the CID

[hex]

(when (and hex (not= hex "0x"))

(cond

(and (string/starts-with? hex "0xe40101"))

;; content type can be 2 or 4 bytes

;; we expect 1b20 (hash algorithm and hash length 64)

;; before the hash so we split the contenthash there

(when-let [hash (second (string/split hex "1b20"))]

(when (= 0x20 (count hash)))

{:namespace :swarm

:hash hash})

(and (= 78 (count hex))

(string/starts-with? hex "0xe3010170"))

;; for retrocompatibility with old CIDv0

{:namespace :ipfs

:hash (-> hex

(subs 10)

hex/decode

b58/encode)}

(and (= 78 (count hex))

(string/starts-with? hex "0xe30101"))

;; new CIDv1

{:namespace :ipfs

:hash (str "z" (-> hex

(subs 6)

hex/decode

b58/encode))})))

(defn url [hex]

(let [{:keys [namespace hash]} (decode (ethereum/normalized-address hex))]

(case namespace

:ipfs (str "https://ipfs.infura.io/ipfs/" hash)

"")))

(fx/defn cat

[cofx {:keys [contenthash on-success on-failure]}]

(let [{:keys [namespace hash]} (decode contenthash)]

(when (= namespace :ipfs)

(ipfs/cat cofx

{:hash hash

:on-success on-success

:on-failure on-failure}))))