From 6acfec81419370b245f6f66e3472e56395e7a9aa Mon Sep 17 00:00:00 2001
From: Xmader <xmader@outlook.com>
Date: Wed, 25 Nov 2020 16:24:27 -0500
Subject: [PATCH] refactor: get ipfs ref

---
 src/cli.ts       |  4 +--
 src/mscz.ts      | 69 ++++++++++++++++++++++++++++++++++++++++--------
 src/scoreinfo.ts | 25 +++---------------
 3 files changed, 64 insertions(+), 34 deletions(-)

diff --git a/src/cli.ts b/src/cli.ts
index dfe4f03..53e92f3 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -3,7 +3,7 @@
 /* eslint-disable no-void */
 
 import fs from 'fs'
-import { fetchMscz } from './mscz'
+import { fetchMscz, MSCZ_URL_SYM } from './mscz'
 import { loadMscore, INDV_DOWNLOADS, WebMscore } from './mscore'
 import { ScoreInfoHtml } from './scoreinfo'
 import { escapeFilename } from './utils'
@@ -59,7 +59,7 @@ void (async () => {
     await fetchMscz(scoreinfo)
 
     spinner.info('MSCZ file loaded')
-    spinner.info(`File URL: ${scoreinfo.msczUrl}`)
+    spinner.info(`File URL: ${scoreinfo.store.get(MSCZ_URL_SYM) as string}`)
     spinner.start()
 
     // load score using webmscore
diff --git a/src/mscz.ts b/src/mscz.ts
index 72df082..e3b338f 100644
--- a/src/mscz.ts
+++ b/src/mscz.ts
@@ -2,23 +2,70 @@
 import { assertRes, getFetch } from './utils'
 import { ScoreInfo } from './scoreinfo'
 
-const MSCZ_BUF_SYM = Symbol('msczBufferP')
+export const MSCZ_BUF_SYM = Symbol('msczBufferP')
+export const MSCZ_URL_SYM = Symbol('msczUrl')
+export const MAIN_CID_SYM = Symbol('mainCid')
+
+const IPNS_KEY = 'QmSdXtvzC8v8iTTZuj5cVmiugnzbR1QATYRcGix4bBsioP'
+const IPNS_RS_URL = `https://ipfs.io/api/v0/dag/resolve?arg=/ipns/${IPNS_KEY}`
+
+export const getMainCid = async (scoreinfo: ScoreInfo, _fetch = getFetch()): Promise<string> => {
+  // look for the persisted msczUrl inside scoreinfo
+  let result = scoreinfo.store.get(MAIN_CID_SYM) as string
+  if (result) {
+    return result
+  }
+
+  const r = await _fetch(IPNS_RS_URL)
+  assertRes(r)
+  const json = await r.json()
+  result = json.Cid['/']
+
+  scoreinfo.store.set(MAIN_CID_SYM, result) // persist to scoreinfo
+  return result
+}
+
+export const loadMsczUrl = async (scoreinfo: ScoreInfo, _fetch = getFetch()): Promise<string> => {
+  // look for the persisted msczUrl inside scoreinfo
+  let result = scoreinfo.store.get(MSCZ_URL_SYM) as string
+  if (result) {
+    return result
+  }
+
+  const mainCid = await getMainCid(scoreinfo, _fetch)
+
+  const url = scoreinfo.getMsczCidUrl(mainCid)
+  const r0 = await _fetch(url)
+  // ipfs-http-gateway specific error
+  // may read further error msg as json
+  if (r0.status !== 500) {
+    assertRes(r0)
+  }
+  const cidRes: { Key: string; Message: string } = await r0.json()
+
+  const cid = cidRes.Key
+  if (!cid) {
+    // read further error msg
+    const err = cidRes.Message
+    if (err.includes('no link named')) { // file not found
+      throw new Error('score not in dataset')
+    } else {
+      throw new Error(err)
+    }
+  }
+  result = `https://ipfs.infura.io/ipfs/${cid}`
+
+  scoreinfo.store.set(MSCZ_URL_SYM, result) // persist to scoreinfo
+  return result
+}
 
 export const fetchMscz = async (scoreinfo: ScoreInfo, _fetch = getFetch()): Promise<ArrayBuffer> => {
   let msczBufferP = scoreinfo.store.get(MSCZ_BUF_SYM) as Promise<ArrayBuffer> | undefined
 
   if (!msczBufferP) {
-    const url = scoreinfo.msczCidUrl
     msczBufferP = (async (): Promise<ArrayBuffer> => {
-      const r0 = await _fetch(url)
-      // ipfs-http-gateway specific error
-      // may read further error msg as json
-      if (r0.status !== 500) {
-        assertRes(r0)
-      }
-      const cidRes = await r0.json()
-
-      const r = await _fetch(scoreinfo.loadMsczUrl(cidRes))
+      const url = await loadMsczUrl(scoreinfo, _fetch)
+      const r = await _fetch(url)
       assertRes(r)
       const data = await r.arrayBuffer()
       return data
diff --git a/src/scoreinfo.ts b/src/scoreinfo.ts
index 406a622..9053dfe 100644
--- a/src/scoreinfo.ts
+++ b/src/scoreinfo.ts
@@ -2,7 +2,6 @@
 import { getFetch, escapeFilename } from './utils'
 
 export abstract class ScoreInfo {
-  private readonly IPNS_KEY = 'QmSdXtvzC8v8iTTZuj5cVmiugnzbR1QATYRcGix4bBsioP';
   private readonly RADIX = 20;
 
   abstract id: number;
@@ -18,28 +17,12 @@ export abstract class ScoreInfo {
     return escapeFilename(this.title)
   }
 
-  get msczIpfsRef (): string {
-    return `/ipns/${this.IPNS_KEY}/${this.idLastDigit}/${this.id}.mscz`
+  public getMsczIpfsRef (mainCid: string): string {
+    return `/ipfs/${mainCid}/${this.idLastDigit}/${this.id}.mscz`
   }
 
-  get msczCidUrl (): string {
-    return `https://ipfs.io/api/v0/block/stat?arg=${this.msczIpfsRef}`
-  }
-
-  public msczUrl: string;
-  public loadMsczUrl (cidRes: { Key: string; Message: string }): string {
-    const cid = cidRes.Key
-    if (!cid) {
-      // read further error msg
-      const err = cidRes.Message
-      if (err.includes('no link named')) { // file not found
-        throw new Error('score not in dataset')
-      } else {
-        throw new Error(err)
-      }
-    }
-    this.msczUrl = `https://ipfs.infura.io/ipfs/${cid}`
-    return this.msczUrl
+  public getMsczCidUrl (mainCid: string): string {
+    return `https://ipfs.infura.io:5001/api/v0/block/stat?arg=${this.getMsczIpfsRef(mainCid)}`
   }
 }