Merge Conflicts (#41)

Co-authored-by: Sayan Datta <sayan@Sayans-MacBook-Air.local> Reviewed-on: sagnik/Project_Velocity#41
2026-04-28 11:32:56 +05:30
parent 61258978e1
commit 7ee51543d9
158 changed files with 23889 additions and 87196 deletions
--- a/backend/migrations/runner.py
+++ b/backend/migrations/runner.py
@@ -0,0 +1,102 @@
+from __future__ import annotations
+
+import hashlib
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Iterable
+
+
+MIGRATIONS_DIR = Path(__file__).resolve().parent / "versions"
+
+
+@dataclass(frozen=True)
+class Migration:
+    version: str
+    name: str
+    path: Path
+    checksum: str
+    sql: str
+
+
+def _checksum(sql: str) -> str:
+    return hashlib.sha256(sql.encode("utf-8")).hexdigest()
+
+
+def discover_migrations(directory: Path = MIGRATIONS_DIR) -> list[Migration]:
+    if not directory.exists():
+        return []
+
+    migrations: list[Migration] = []
+    for path in sorted(directory.glob("*.sql")):
+        version, _, name = path.stem.partition("_")
+        if not version or not name:
+            raise ValueError(f"Invalid migration filename: {path.name}")
+        sql = path.read_text(encoding="utf-8")
+        migrations.append(
+            Migration(
+                version=version,
+                name=name,
+                path=path,
+                checksum=_checksum(sql),
+                sql=sql,
+            )
+        )
+
+    seen: set[str] = set()
+    for migration in migrations:
+        if migration.version in seen:
+            raise ValueError(f"Duplicate migration version: {migration.version}")
+        seen.add(migration.version)
+    return migrations
+
+
+async def ensure_migration_table(conn) -> None:
+    await conn.execute(
+        """
+        CREATE TABLE IF NOT EXISTS schema_migrations (
+            version TEXT PRIMARY KEY,
+            name TEXT NOT NULL,
+            checksum TEXT NOT NULL,
+            applied_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+        )
+        """
+    )
+
+
+async def applied_versions(conn) -> dict[str, str]:
+    await ensure_migration_table(conn)
+    rows = await conn.fetch("SELECT version, checksum FROM schema_migrations")
+    return {row["version"]: row["checksum"] for row in rows}
+
+
+async def apply_migrations(conn, migrations: Iterable[Migration] | None = None) -> list[str]:
+    pending = list(migrations if migrations is not None else discover_migrations())
+    applied = await applied_versions(conn)
+    applied_now: list[str] = []
+
+    for migration in pending:
+        existing_checksum = applied.get(migration.version)
+        if existing_checksum == migration.checksum:
+            continue
+        if existing_checksum and existing_checksum != migration.checksum:
+            raise RuntimeError(
+                f"Migration checksum mismatch for {migration.version}; "
+                "create a new migration instead of editing an applied one."
+            )
+
+        transaction = conn.transaction()
+        async with transaction:
+            await conn.execute(migration.sql)
+            await conn.execute(
+                """
+                INSERT INTO schema_migrations (version, name, checksum)
+                VALUES ($1, $2, $3)
+                """,
+                migration.version,
+                migration.name,
+                migration.checksum,
+            )
+        applied_now.append(migration.version)
+
+    return applied_now
+