#!/usr/bin/env python
from __future__ import print_function
import sys
import os
import re

def append2x(content, dir):
    header = """/* BEGIN 2X BLOCK -- DO NOT EDIT MANUALLY -- USE 2XIZE */
@media (min-resolution: 1.25dppx) {\n"""
    footer = "\n}\n"
    output = ""
    for line in content.split("\n"):
        matches = re.match('(.+chrome://zotero/skin/)(.+(?<!@2x)\.png)(.+)', line)
        
        if not matches:
            # Skip lines that are indented but don't reference an image, which are
            # hopefully rule lines
            if re.match('\s', line):
                continue
            # Pass other lines through as is, since those are likely selector lines
            output += line
            continue
        
        png = matches.group(2)
        png2x = png.replace('.png', '@2x.png')
        
        if os.path.exists(os.path.join(root_dir, png2x)):
            output += matches.group(1) + png2x + matches.group(3)
        else:
            output += line
    output += "}"
    # Collapse all spaces
    output = re.sub("\s+", " ", output)
    # Add space before and after "{"
    output = re.sub("(?!: ){\s*", " { ", output)
    # Add newline after }
    output = re.sub("}", "}\n", output)
    # Add space before }
    output = re.sub("(?!: )}", " }", output)
    # Strip comments
    output = re.sub("/\*[^*]+\*/", "", output)
    # Remove all blocks without 2x rules
    output = "\n".join(["\t" + line for line in output.split("\n") if "2x.png" in line])
    return header + output + footer

if __name__ == "__main__":
    if len(sys.argv) < 2:
        print("""Appends 2x image rules to a CSS file for all images with @2x.png versions in the same directory

Usage: {0} /path/to/css/file [/path/to/image/directory]""".format(sys.argv[0]))
        sys.exit(1)
    
    css_file = sys.argv[1]
    if not os.path.exists(css_file):
        print("File not found: " + css_file)
        sys.exit(1)
    
    try:
        root_dir = sys.argv[2]
        if not os.path.exists(root_dir):
            print("Directory not found: " + root_dir)
            sys.exit(1)
        
        if not os.path.isdir(root_dir):
            print("{0} is not a directory".format(root_dir))
            sys.exit(1)
    except IndexError:
        root_dir = os.path.dirname(os.path.realpath(css_file))
    
    # Get file contents through 2x block, which has to be at the end
    css = ""
    with open(css_file) as f:
        for line in f:
            if "BEGIN 2X BLOCK" in line:
                break
            css += line
    css = css.strip()
    
    # Add 2x block
    css += "\n\n\n" + append2x(css, root_dir)
    
    with open(css_file, 'w') as f:
        f.write(css)