From 5984370a72d448b07d62ed8f7e20b4dffe30339a Mon Sep 17 00:00:00 2001
From: Brad Spencer <spencer@jacknife.org>
Date: Sat, 4 Jun 2022 23:15:41 -0300
Subject: [PATCH] Add a --preview option

You can use this option to see if you like the output before
you spend time computing the actual prime number.
---
 src/primify/base.py | 37 ++++++++++++++++++++++++-------------
 src/primify/cli.py  |  9 ++++++++-
 2 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/src/primify/base.py b/src/primify/base.py
index 5134da60..f0b08dab 100644
--- a/src/primify/base.py
+++ b/src/primify/base.py
@@ -146,7 +146,10 @@ def quantized_image_to_number(image: Image.Image) -> ImageNumber:
 
         return ImageNumber(value=int(digits), image_width=image.width)
 
-    def get_prime(self) -> ImageNumber:
+    def get_prime(
+            self,
+            preview: False
+    ) -> ImageNumber:
 
         with console.status(f"Converting {self.image_path} into number."):
             quantized_image = PrimeImage.quantize_image(self.im)
@@ -165,23 +168,31 @@ def get_prime(self) -> ImageNumber:
 
         with console.status("Searching for a similar looking prime."):
 
-            # initiate helping prime finder. Much faster than just using nextprime()
-            n_processes = max(
-                1, mp.cpu_count() - 1
-            )  # at least one core should remain free
+            # are we actually going to search?
+            if not preview:
 
-            console.log(
-                f"Initializing multi-process prime finder with {n_processes} workers."
-            )
-            prime_finder = NextPrimeFinder(
-                value=image_number.value, n_workers=n_processes
-            )
-            next_prime = prime_finder.find_next_prime()
+                # initiate helping prime finder. Much faster than just using nextprime()
+                n_processes = max(
+                    1, mp.cpu_count() - 1
+                )  # at least one core should remain free
+
+                console.log(
+                    f"Initializing multi-process prime finder with {n_processes} workers."
+                )
+                prime_finder = NextPrimeFinder(
+                    value=image_number.value, n_workers=n_processes
+                )
+                next_prime = prime_finder.find_next_prime()
+
+            else:
+                # just use the original image number as a preview if we aren't
+                # searching for a prime
+                next_prime = image_number.value
 
             # turn result back into a formated number
             result = ImageNumber(next_prime, image_number.image_width)
 
             console.print(str(result), style="black on white")
             self.output_file_path.write_text(str(result))
-            console.log(f"Saved prime to {self.output_file_path}!")
+            console.log(f"Saved {'preview' if preview else 'prime'} to {self.output_file_path}!")
             return result
diff --git a/src/primify/cli.py b/src/primify/cli.py
index 99c87795..3b19db3b 100644
--- a/src/primify/cli.py
+++ b/src/primify/cli.py
@@ -56,6 +56,13 @@ def parse_args(args):
         dest="output_file",
     )
 
+    parser.add_argument(
+        "--preview",
+        "-n",
+        action="store_true",
+        help="Emit a preview number that is not prime."
+    )
+
     return parser.parse_args(args)
 
 
@@ -73,7 +80,7 @@ def main(args):
         output_file_path=args.output_file,
     )
 
-    a.get_prime()
+    a.get_prime(preview=args.preview)
 
 
 def run():