51 lines
1.7 KiB
Python
51 lines
1.7 KiB
Python
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"""Version-to-version comparison for artifacts (HUX-04).
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Text artifacts get a unified diff from ``difflib``; anything that is not
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valid UTF-8, or whose artifact type is binary, is described by sizes and
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hashes only so the UI never tries to render bytes as text.
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"""
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from __future__ import annotations
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import difflib
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import hashlib
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from typing import Any
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TEXT_TYPES = frozenset({"markdown", "code", "html", "svg", "json", "csv"})
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def is_text_type(artifact_type: str) -> bool:
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"""True for artifact types whose content is served as UTF-8 text."""
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return artifact_type in TEXT_TYPES
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def decode_text(data: bytes) -> str | None:
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"""UTF-8 decode, or None when the bytes are not text."""
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try:
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return data.decode("utf-8")
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except UnicodeDecodeError:
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return None
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def unified(artifact_type: str, older: bytes, newer: bytes, from_n: int, to_n: int) -> dict[str, Any]:
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"""Diff record ``{"from", "to", "unified"|"binary"}`` for two versions."""
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record: dict[str, Any] = {"from": from_n, "to": to_n}
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old_text = decode_text(older) if is_text_type(artifact_type) else None
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new_text = decode_text(newer) if is_text_type(artifact_type) else None
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if old_text is None or new_text is None:
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record["binary"] = {
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"from_bytes": len(older),
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"to_bytes": len(newer),
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"from_hash": "sha256:" + hashlib.sha256(older).hexdigest(),
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"to_hash": "sha256:" + hashlib.sha256(newer).hexdigest(),
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}
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return record
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lines = difflib.unified_diff(
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old_text.splitlines(keepends=True),
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new_text.splitlines(keepends=True),
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fromfile=f"v{from_n}",
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tofile=f"v{to_n}",
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)
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record["unified"] = "".join(lines)
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return record
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