Add script for downloading puzzlescript games by url.

Add capability to download itch.io puzzlescript games (experimental).
Update readme.

README.md

@@ -8,9 +8,16 @@ PuzzleScript games are usually online at the main PuzzleScript site:
 https://www.puzzlescript.net/
 
 To play games in the core, you will need to download the source for the game and save it as a `.pz` file.
-The normal way to do this is to click the "hack" link on the game to go to the PuzzleScript editor, then
+The normal way to do this is to click the "hack" or "sourcecode" link on the game to go to the PuzzleScript editor, then
 copy/paste the entire contents of the program into a file with extension `.pz`.
 
+There is also a Python utility script in `tools/get_game.py` that can download PuzzleScript game source given a url. Typical
+use would be:
+
+    python3 tools/get_game.py --url=https://www.puzzlescript.net/play.html?p=2ba817426abc9fcbe9b9980fc4c02519 --output-title=.pz
+
+This would download and save the file `One_Microban_level.pz`.
+
 You can also find many games in the Accessible PuzzleScript repository. For these, save the `script.txt` file
 into a file with extension `.pz`.
 https://github.com/philschatz/puzzlescript/tree/master/games
@@ -74,6 +81,7 @@ content.
 ## Future work
 
 * Support more platforms for binary releases.
+* Support [Pattern:Script](https://github.com/ClementSparrow/Pattern-Script/)
 * Add support for background music.
 * Add volume level control and other audio options.
 * Incorporate more accessibility features from: https://github.com/philschatz/puzzlescript
@@ -211,15 +219,18 @@ BuildKit build.
 
 ## References
 
-PuzzleScript project:
+PuzzleScript project
 https://github.com/increpare/PuzzleScript
 
 Accessible PuzzleScript
 https://github.com/philschatz/puzzlescript
 
-PuzzleScript Plus:
+PuzzleScript Plus
 https://github.com/Auroriax/PuzzleScriptPlus
 
+Pattern:Script
+https://github.com/ClementSparrow/Pattern-Script/
+
 For making the retroarch core, I followed this tutorial:
 https://web.archive.org/web/20190219134028/http://www.beardypig.com/2016/01/22/emulator-build-along-2/
 
@@ -229,8 +240,8 @@ https://github.com/Narkhos/Puzzlescript-Wrapper
 QuickJS
 https://bellard.org/quickjs/
 
-Docs for using V8:
+Docs for using V8
 https://v8.dev/docs/
 
-Linaro toolchain:
+Linaro toolchain
 https://releases.linaro.org/components/toolchain/binaries/

tools/get_game.py

@@ -0,0 +1,94 @@
+'''
+Download a PuzzleScript game
+
+Given URL to play game on PuzzleScript, this script downloads source and saves to a file.
+
+'''
+
+import argparse
+import codecs
+import re
+import requests
+
+ESCAPE_SEQUENCE_RE = re.compile(r'''
+    ( \\U........      # 8-digit hex escapes
+    | \\u....          # 4-digit hex escapes
+    | \\x..            # 2-digit hex escapes
+    | \\[0-7]{1,3}     # Octal escapes
+    | \\N\{[^}]+\}     # Unicode characters by name
+    | \\[\\'"abfnrtv]  # Single-character escapes
+    )''', re.UNICODE | re.VERBOSE)
+
+def decode_escapes(s):
+    ''' Decode Python escape sequences in a string containing unicode '''
+    # Basic problem is that decode with unicode-escape is broken in Python, doesn't work with unicode
+    # So only apply to actual escape parts, which are guaranteed to be just ascii
+    def decode_match(match):
+        return codecs.decode(match.group(0), 'unicode-escape')
+    return ESCAPE_SEQUENCE_RE.sub(decode_match, s)
+
+def find_title(content):
+    lines = content.split('\n')
+    for line in lines:
+        spl = line.split(' ')
+        if spl[0].upper() == 'TITLE':
+            return ' '.join(spl[1:])
+    raise RuntimeError("Could not find title in prelude")
+
+def convert_dangerous(txt):
+    txt = txt.replace('-', '_')
+    txt = txt.replace(' ', '_')
+    txt = txt.replace("'", '_')
+    return txt
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description='Download PuzzleScript game source files')
+    parser.add_argument('--url', required=True, help="URL for playing game on PuzzleScript.net or itch.io")
+    parser.add_argument('--output', help="Output filename to save game contents to (if not given will display to stdout)")
+    parser.add_argument('--output-title', help="Save to filename given prefixed with game title")
+    args = parser.parse_args()
+    if "itch.io" in args.url:
+        # For itch.io downloads, first get contents
+        r = requests.get(args.url)
+        # Search for cdn link to game itself
+        m = re.search(r'(https://\S+\.hwcdn.net/\S+/index.html)', r.text)
+        if not m:
+            print('Could not find hwcdn link')
+            exit(-1)
+        # Get contents of cdn link
+        cdn_url = m.group(0)
+        r = requests.get(cdn_url)
+        text = r.content.decode('utf-8')
+        # Regex looks for the sourcecode, inside quotes allowing escapes inside string
+        pat = r'''sourceCode="([^"\\]*(\\.[^"\\]*)*)"'''
+        m = re.search(pat, text)
+        if m is None:
+            # Try minified version
+            mpat = r'''compile\(-1, "([^"\\]*(\\.[^"\\]*)*)"'''
+            m = re.search(mpat, text)
+            if m is None:
+                print("Could not find sourceCode in cdn result")
+                exit(-1)
+        source = m.group(1)
+        # We have the source in escaped form, need to unescape it (allowing unicode)
+        content = decode_escapes(source)
+    else:
+        spl = args.url.split('=')
+        if len(spl) < 2:
+            print("ERROR: Could not parse URL, must be in form: https://www.puzzlescript.net/play.html?p=IDENTIFIER")
+            exit(-1)
+        id = spl[-1]
+        dl_url = f"https://api.github.com/gists/{id}"
+        r = requests.get(dl_url)
+        data = r.json()
+        content = data['files']['script.txt']['content']
+    if args.output_title:
+        title = find_title(content)
+        safe_title = convert_dangerous(title)
+        args.output = f"{safe_title}{args.output_title}"
+    if args.output:
+        with open(args.output, "w") as fout:
+            fout.write(content)
+        print(f"Wrote {len(content)} bytes of output to file: {args.output}")
+    else:
+        print(content)