"""
Migration script for old 'yaml' and 'json' cassettes

.. warning:: Backup your cassettes files before migration.

It merges and deletes the request obsolete keys (protocol, host, port, path)
into new 'uri' key.
Usage::

    python -m vcr.migration PATH

The PATH can be path to the directory with cassettes or cassette itself
"""

import json
import os
import re
import shutil
import sys
import tempfile


PARTS = [
    'protocol',
    'host',
    'port',
    'path',
]


def build_uri(**parts):
    return "{protocol}://{host}:{port}{path}".format(**parts)


def migrate_json(in_fp, out_fp):
    data = json.load(in_fp)
    for item in data:
        req = item['request']
        uri = dict((k, req.pop(k)) for k in PARTS)
        req['uri'] = build_uri(**uri)
    json.dump(data, out_fp, indent=4)


def migrate_yml(in_fp, out_fp):
    migrated = False
    uri = dict.fromkeys(PARTS, None)
    for line in in_fp:
        for part in uri:
            match = re.match('\s+{0}:\s(.*)'.format(part), line)
            if match:
                uri[part] = match.group(1)
                break
        else:
            out_fp.write(line)

        if None not in uri.values():  # if all uri parts are collected
            out_fp.write("    uri: {0}\n".format(build_uri(**uri)))
            uri = dict.fromkeys(PARTS, None)  # reset dict
            migrated = True
    if not migrated:
        raise RuntimeError("migration failed")


def migrate(file_path, migration_fn):
    # because we assume that original files can be reverted
    # we will try to copy the content. (os.rename not needed)
    with tempfile.TemporaryFile(mode='w+') as out_fp:
        with open(file_path, 'r') as in_fp:
            migration_fn(in_fp, out_fp)
        with open(file_path, 'w') as in_fp:
            out_fp.seek(0)
            shutil.copyfileobj(out_fp, in_fp)


def try_migrate(path):
    try:  # try to migrate as json
        migrate(path, migrate_json)
    except Exception:  # probably the file is not a json
        try:  # let's try to migrate as yaml
            migrate(path, migrate_yml)
        except Exception:  # oops probably the file is not a cassette
            return False
    return True


def main():
    if len(sys.argv) != 2:
        raise SystemExit("Please provide path to cassettes directory or file. "
                         "Usage: python -m vcr.migration PATH")

    path = sys.argv[1]
    if not os.path.isabs(path):
        path = os.path.abspath(path)
    files = [path]
    if os.path.isdir(path):
        files = (os.path.join(root, name)
                 for (root, dirs, files) in os.walk(path)
                 for name in files)
    for file_path in files:
            migrated = try_migrate(file_path)
            status = 'OK' if migrated else 'FAIL'
            sys.stderr.write("[{0}] {1}\n".format(status, file_path))
    sys.stderr.write("Done.\n")

if __name__ == '__main__':
    main()