#!/usr/bin/python3
"""Source for binary data encoded inline in the manifest

This source can be used to transport data in the source
section of the manifest. Each resource is ascii-encoded
in the `data` property, where the encoding is specified
in the `encoding` property. The resources is content
addressed via the hash value of the raw data before the
ascii encoding. This hash value is verified after the
resource is decoded and written to the store.
"""


import base64
import contextlib
import lzma
import os
import sys
from typing import Dict

from osbuild import sources
from osbuild.util.checksum import verify_file

SCHEMA = """
"definitions": {
  "item": {
    "description": "Inline data indexed by their checksum",
    "type": "object",
    "additionalProperties": false,
    "patternProperties": {
      "(md5|sha1|sha256|sha384|sha512):[0-9a-f]{32,128}": {
        "type": "object",
        "additionalProperties": false,
        "required": ["encoding", "data"],
        "properties": {
          "encoding": {
            "description": "The specific encoding of `data`",
            "enum": ["base64", "lzma+base64"]
          },
          "data": {
            "description": "The ascii encoded raw data",
            "type": "string"
          }
        }
      }
    }
  }
},
"additionalProperties": false,
"required": ["items"],
"properties": {
  "items": {"$ref": "#/definitions/item"}
}
"""


class InlineSource(sources.SourceService):

    content_type = "org.osbuild.files"

    def fetch_all(self, items: Dict) -> None:
        filtered = filter(lambda i: not self.exists(i[0], i[1]), items.items())  # discards items already in cache

        for args in filtered:
            self.fetch_one(*args)

    def fetch_one(self, checksum, desc):
        target = os.path.join(self.cache, checksum)
        floating = os.path.join(self.tmpdir, checksum)

        if os.path.isfile(target):
            return

        encoding = desc["encoding"]
        if encoding == "base64":
            data = base64.b64decode(desc["data"])
        elif encoding == "lzma+base64":
            data = base64.b64decode(desc["data"])
            data = lzma.decompress(data)
        else:
            raise RuntimeError(f"Unknown encoding {encoding}")

        # Write the bits to disk and then verify the checksum
        # This ensures that 1) the data is ok and that 2) we
        # wrote them correctly as well
        with open(floating, "wb") as f:
            f.write(data)

        if not verify_file(floating, checksum):
            raise RuntimeError(f"Checksum mismatch for {format(checksum)}")

        with contextlib.suppress(FileExistsError):
            os.rename(floating, target)


def main():
    service = InlineSource.from_args(sys.argv[1:])
    service.main()


if __name__ == '__main__':
    main()