#!/usr/bin/env python3

import re
import subprocess

class change:
    def __init__(self, file, new, ptr, before, after):
        self.file = file  # filename 
        self.new = new    # new()
        self.ptr = ptr    # pointer.Of()
        # lines before and after for context
        self.before = before
        self.after = after

    def is_copacetic(self):
        # simple cases where type is inferred
        # pointer.Of(val) => new(val)
        if self.new == self.ptr.replace("-pointer.Of", "+new"):
            return True 

        # within the pointer package
        # Of(val) => new(val)
        if self.file.startswith("helper/pointer") \
            and self.new == self.ptr.replace("-Of(", "+new("):
            return True

        # getting a bit silly now, detect when the type is specified
        # pointer.Of[type](val) => new(type(val))
        groups = re.match(r"-pointer.Of\[(?P<type>[\d\w\.]+)\]\((?P<val>.*)\)", self.ptr)
        if groups:
            type = groups.group("type")
            val = groups.group("val")
            # strip occasional type redundancy
            # pointer.Of[type](type(val)) => pointer.Of[type](val)
            val = val.lstrip(f"{type}(").rstrip(")")
            expect = f"+new({type}({val})"
            # little variations on the suffix
            if self.new == expect \
                or self.new == expect + ")" \
                or self.new == expect + "),":
                return True
        return False

    def __repr__(self):
        return f'{self.file=} {self.new=} {self.ptr=}'

    def __str__(self):
        return f"""\
>>> {self.file}
{self.before}
>>> {self.ptr}
>>> {self.new}
{self.after}"""


if __name__ == '__main__':
    lines = subprocess.check_output(
        # at the time of this script, HEAD~3 is just before these changes.
        ["git", "diff", "HEAD~3", "HEAD", "--word-diff=porcelain"]
    ).decode("utf-8").splitlines()
    
    # clean up "~"-only lines
    lines = [l for l in lines if l != '~']

    # collect changes
    changes = []
    file = None
    for i, line in enumerate(lines):
        if line.startswith('---'):
            file = line.split('--- a/')[1]
        if line.startswith("+new("):
            # each +new should have a -pointer.Of right before it,
            # so we have everything we need from here.
            changes.append(change(
                file=file,
                new=line,
                ptr=lines[i-1],
                # lines before and after for context
                before="\n".join(lines[i-3:i-1]),
                after="\n".join(lines[i+1:i+4]),
            ))
    
    for ch in changes:
        if not ch.is_copacetic():
            print(ch)

    print(f"\nHOW MANY: {len(changes)}")