Integrate pdfCropMargins for cropping PDFs (#29)

index.js

@@ -10,7 +10,8 @@ const serve = require('koa-static')
 const { mkdirp } = require('mkdirp')
 const fs = require('fs')
 const { spawn } = require('child_process')
-const { extname, basename, dirname } = require('path')
+const { join, extname, basename, dirname } = require('path')
+const resolvepath = require('path').resolve
 const FileType = require('file-type')
 const { transliterate } = require('transliteration')
 const sanitize = require('sanitize-filename')
@@ -418,6 +419,55 @@ router.post('/upload', async (ctx, next) => {
         })
         return
       }
+
+    } else if (mimetype == 'application/pdf' && ctx.request.body.pdfcropmargins) {
+      const dir = dirname(ctx.request.file.path)
+      const base = basename(ctx.request.file.path, '.pdf')
+      const outfile = resolvepath(join(dir, `${base}_cropped.pdf`))
+      let p = new Promise((resolve, reject) => {
+        let stderr = ''
+        const pdfcropmargins = spawn('pdfcropmargins', ['-s', '-u', '-o', outfile, basename(ctx.request.file.path)], {
+          // stdio: 'inherit',
+          cwd: dirname(ctx.request.file.path)
+        })
+        pdfcropmargins.once('error', function (err) {
+          fs.unlink(ctx.request.file.path, (err) => {
+            if (err) console.error(err)
+            else console.log('Removed file', ctx.request.file.path)
+          })
+          reject('pdfcropmargins error: ' + err)
+        })
+        pdfcropmargins.once('close', (code) => {
+          fs.unlink(ctx.request.file.path, (err) => {
+            if (err) console.error(err)
+            else console.log('Removed file', ctx.request.file.path)
+          })
+          if (code !== 0) {
+            reject('pdfcropmargins error code: ' + code + '\n' + stderr)
+            return
+          }
+
+          resolve(outfile)
+        })
+        pdfcropmargins.stdout.on('data', function (str) {
+          stderr += str
+          console.log('pdfcropmargins: ' + str)
+        })
+        pdfcropmargins.stderr.on('data', function (str) {
+          stderr += str
+          console.log('pdfcropmargins: ' + str)
+        })
+      })
+      try {
+        data = await p
+      } catch (err) {
+        flash(ctx, {
+          success: false,
+          message: err.replaceAll(basename(ctx.request.file.path), "infile.pdf").replaceAll(outfile, "outfile.pdf")
+        })
+        return
+      }
+
     } else {
       // No conversion
       data = ctx.request.file.path