feat(core): add output_condition option (#620) [skip ci]

source/app/action/index.mjs

@@ -93,6 +93,7 @@ async function wait(seconds) {
       retries,
       "retries.delay":retries_delay,
       "output.action":_action,
+      "output.condition":_output_condition,
       delay,
       ...config
     } = metadata.plugins.core.inputs.action({core})
@@ -321,9 +322,31 @@ async function wait(seconds) {
       throw error ?? new Error("Could not render metrics")
     info("Status", "complete")
 
-    //Save output to renders output folder
+    //Output condition
     info.break()
     info.section("Saving")
+    info("Output condition", _output_condition)
+    if ((_output_condition === "skip-if-only-metadata-changed")&&((committer.commit) || (committer.pr))) {
+      const {svg} = await import("../metrics/utils.mjs")
+      let data = ""
+      try {
+        data = `${Buffer.from((await committer.rest.repos.getContent({...github.context.repo, ref:`heads/${committer.head}`, path:filename})).data.content, "base64")}`
+      }
+      catch (error) {
+        if (error.response.status !== 404)
+          throw error
+      }
+      const previous = await svg.hash(data)
+      info("Previous hash", previous)
+      const current = await svg.hash(rendered)
+      info("Current hash", current)
+      const changed = (previous !== current)
+      info("Content changed", changed)
+      if (!changed)
+        committer.commit = false
+    }
+
+    //Save output to renders output folder
     if (dryrun)
       info("Actions to perform", "(none)")
     else {

source/app/metrics/utils.mjs

@@ -24,6 +24,7 @@ import fetch from "node-fetch"
 import readline from "readline"
 import emoji from "emoji-name-map"
 import minimatch from "minimatch"
+import crypto from "crypto"
 prism_lang()
 
 //Exports
@@ -413,6 +414,29 @@ export const svg = {
     console.debug("metrics/svg/resize > rendering complete")
     return {resized, mime}
   },
+  /**Hash a SVG (removing its metadata first)*/
+  async hash(rendered) {
+    //Handle empty case
+    if (!rendered)
+      return null
+    //Instantiate browser if needed
+    if (!svg.resize.browser) {
+      svg.resize.browser = await puppeteer.launch()
+      console.debug(`metrics/svg/hash > started ${await svg.resize.browser.version()}`)
+    }
+    //Compute hash
+    const page = await svg.resize.browser.newPage()
+    await page.setContent(rendered, {waitUntil:["load", "domcontentloaded", "networkidle2"]})
+    const data = await page.evaluate(async () => {
+      document.querySelector("footer")?.remove()
+      return document.querySelector("svg").outerHTML
+    })
+    const hash = crypto.createHash("md5").update(data).digest("hex")
+    //Result
+    await page.close()
+    console.debug(`metrics/svg/hash > MD5=${hash}`)
+    return hash
+  },
   /**Render twemojis */
   async twemojis(rendered, {custom = true} = {}) {
     //Load emojis