dataforge/stores/duckdb.py

"""DuckDB table-store implementation for local warehouse repair proofs."""

from __future__ import annotations

import json
import os
from datetime import UTC, datetime
from pathlib import Path
from typing import Any

from dataforge.detectors.base import Schema
from dataforge.repairers.base import ProposedFix
from dataforge.stores.base import StoreApplyReceipt, TableStore, TableStoreError
from dataforge.stores.patch_plan import PatchOperation, PatchPlan, RowIdentity
from dataforge.stores.sql import ensure_safe_relation, quote_identifier, sql_literal
from dataforge.table import Table, TableLike, cell_value, column_names, row_count
from dataforge.transactions.log import (
    append_applied_event,
    append_created_transaction,
    append_reverted_event,
    load_transaction,
    sha256_bytes,
)
from dataforge.transactions.txn import RepairTransaction, generate_txn_id


class DuckDBStore(TableStore):
    """Local DuckDB relation adapter with real apply and rollback."""

    backend = "duckdb"

    def __init__(
        self,
        *,
        database_path: Path,
        relation: str,
        row_identity_columns: tuple[str, ...] = (),
        target: str | None = None,
    ) -> None:
        self.database_path = database_path.resolve()
        self.relation = ensure_safe_relation(relation)
        self.row_identity_columns = row_identity_columns
        self.target = (
            target or f"warehouse://duckdb?database={self.database_path}&relation={relation}"
        )

    def _connect(self, *, read_only: bool) -> Any:
        try:
            import duckdb
        except ImportError as exc:
            raise TableStoreError("DuckDB table-store support requires duckdb.") from exc
        return duckdb.connect(str(self.database_path), read_only=read_only)

    def read_table(self) -> TableLike:
        """Read the configured relation into the DataForge table surface."""
        with self._connect(read_only=True) as connection:
            cursor = connection.execute(f"SELECT * FROM {self.relation}")
            columns = [str(item[0]) for item in cursor.description]
            return Table(
                columns, (dict(zip(columns, row, strict=True)) for row in cursor.fetchall())
            )

    def _identity_for_row(self, table: TableLike, row: int) -> RowIdentity:
        columns = column_names(table)
        if not self.row_identity_columns:
            return RowIdentity(
                kind="unavailable",
                stable=False,
                reason="Warehouse apply requires explicit row identity columns.",
            )
        missing = [column for column in self.row_identity_columns if column not in columns]
        if missing:
            return RowIdentity(
                kind="unavailable",
                columns=self.row_identity_columns,
                stable=False,
                reason="Missing row identity columns: " + ", ".join(missing),
            )
        return RowIdentity(
            kind="column_values",
            columns=self.row_identity_columns,
            values={column: cell_value(table, row, column) for column in self.row_identity_columns},
            stable=True,
            reason="Explicit row identity columns are present in the relation snapshot.",
        )

    def _where_sql(
        self,
        identity: RowIdentity,
        *,
        column: str | None = None,
        value: str | None = None,
    ) -> str:
        clauses = [
            f"{quote_identifier(key)} = {sql_literal(identity.values[key])}"
            for key in identity.columns
        ]
        if column is not None and value is not None:
            clauses.append(f"{quote_identifier(column)} = {sql_literal(value)}")
        return " AND ".join(clauses)

    def build_patch_plan(
        self,
        fixes: list[ProposedFix],
        *,
        schema: Schema | None,
        safety_verdict: str,
        touched_constraints: tuple[str, ...] = (),
        smt_obligations: tuple[str, ...] = (),
    ) -> PatchPlan:
        """Build SQL patch and rollback statements for verified fixes."""
        del schema
        table = self.read_table()
        operations: list[PatchOperation] = []
        for proposed in fixes:
            fix = proposed.fix
            identity = self._identity_for_row(table, fix.row)
            precondition_sql = forward_sql = rollback_sql = None
            verification_sql: tuple[str, ...] = ()
            if identity.stable:
                old_where = self._where_sql(identity, column=fix.column, value=fix.old_value)
                new_where = self._where_sql(identity, column=fix.column, value=fix.new_value)
                precondition_sql = f"SELECT COUNT(*) FROM {self.relation} WHERE {old_where}"
                forward_sql = (
                    f"UPDATE {self.relation} SET {quote_identifier(fix.column)} = "
                    f"{sql_literal(fix.new_value)} WHERE {old_where}"
                )
                rollback_sql = (
                    f"UPDATE {self.relation} SET {quote_identifier(fix.column)} = "
                    f"{sql_literal(fix.old_value)} WHERE {new_where}"
                )
                verification_sql = (f"SELECT COUNT(*) FROM {self.relation} WHERE {new_where}",)
            operations.append(
                PatchOperation.from_cell_fix(
                    fix,
                    relation=self.relation,
                    row_identity=identity,
                    reason=proposed.reason,
                    confidence=proposed.confidence,
                    provenance=proposed.provenance,
                    precondition_sql=precondition_sql,
                    forward_sql=forward_sql,
                    rollback_sql=rollback_sql,
                    verification_sql=verification_sql,
                )
            )

        reason = (
            "DuckDB patch plan is apply-ready."
            if operations and all(operation.row_identity.stable for operation in operations)
            else "DuckDB patch plan is dry-run only until row identity is configured."
        )
        return PatchPlan.new(
            backend=self.backend,
            target=self.target,
            relation=self.relation,
            row_identity_columns=self.row_identity_columns,
            operations=tuple(operations),
            safety_verdict=safety_verdict,
            rows_scanned=row_count(table),
            reason=reason,
            touched_constraints=touched_constraints,
            smt_obligations=smt_obligations,
            audit_metadata={"database": str(self.database_path)},
        )

    def _relation_rows(self, connection: Any) -> list[dict[str, str]]:
        order_by = ""
        if self.row_identity_columns:
            quoted = ", ".join(quote_identifier(column) for column in self.row_identity_columns)
            order_by = f" ORDER BY {quoted}"
        cursor = connection.execute(f"SELECT * FROM {self.relation}{order_by}")
        columns = [str(item[0]) for item in cursor.description]
        return [
            {
                column: "" if value is None else str(value)
                for column, value in zip(columns, row, strict=True)
            }
            for row in cursor.fetchall()
        ]

    def _snapshot_bytes(self, plan: PatchPlan) -> bytes:
        with self._connect(read_only=True) as connection:
            rows = self._relation_rows(connection)
        payload = {
            "schema_version": "table_store_snapshot_v1",
            "backend": self.backend,
            "target": self.target,
            "relation": self.relation,
            "patch_plan_sha256": plan.sha256(),
            "rows": rows,
        }
        return json.dumps(payload, sort_keys=True, separators=(",", ":")).encode("utf-8")

    def _write_snapshot(self, state_root: Path, txn_id: str, payload: bytes) -> Path:
        snapshot_path = state_root.resolve() / ".dataforge" / "snapshots" / f"{txn_id}.bin"
        snapshot_path.parent.mkdir(parents=True, exist_ok=True)
        try:
            with snapshot_path.open("xb") as handle:
                handle.write(payload)
                handle.flush()
                os.fsync(handle.fileno())
        except FileExistsError as exc:
            raise TableStoreError(f"Transaction snapshot already exists: {snapshot_path}") from exc
        return snapshot_path

    def _execute_scalar_int(self, connection: Any, sql: str) -> int:
        value = connection.execute(sql).fetchone()[0]
        return int(value)

    def apply_patch_plan(
        self,
        plan: PatchPlan,
        *,
        state_root: Path | None = None,
    ) -> StoreApplyReceipt:
        """Apply a verified DuckDB patch plan inside a transaction."""
        if plan.backend != self.backend:
            raise TableStoreError(f"Patch plan backend {plan.backend!r} does not match DuckDB.")
        if not plan.apply_supported or not plan.reversible:
            raise TableStoreError(plan.reason)
        state_dir = (state_root or Path.cwd()).resolve()
        txn_id = generate_txn_id()
        snapshot_bytes = self._snapshot_bytes(plan)
        snapshot_path = self._write_snapshot(state_dir, txn_id, snapshot_bytes)
        transaction = RepairTransaction(
            txn_id=txn_id,
            created_at=datetime.now(UTC),
            source_path=self.target,
            source_sha256=sha256_bytes(snapshot_bytes),
            source_snapshot_path=str(snapshot_path),
            fixes=[],
            applied=False,
            source_kind="table_store",
            backend=self.backend,
            patch_plan=plan.model_dump(mode="json"),
        )
        try:
            log_path = append_created_transaction(transaction, log_root=state_dir)
        except Exception:
            snapshot_path.unlink(missing_ok=True)
            raise

        with self._connect(read_only=False) as connection:
            try:
                connection.execute("BEGIN TRANSACTION")
                for sql in plan.preflight_probes:
                    if self._execute_scalar_int(connection, sql) != 1:
                        raise TableStoreError(
                            f"Preflight probe did not match exactly one row: {sql}"
                        )
                for sql in plan.forward_sql:
                    connection.execute(sql)
                for sql in plan.verification_queries:
                    if self._execute_scalar_int(connection, sql) != 1:
                        raise TableStoreError(f"Verification query failed: {sql}")
                post_rows = self._relation_rows(connection)
                post_sha256 = sha256_bytes(
                    json.dumps(post_rows, sort_keys=True, separators=(",", ":")).encode("utf-8")
                )
                connection.execute("COMMIT")
                append_applied_event(log_path, txn_id, post_sha256=post_sha256)
            except Exception:
                connection.execute("ROLLBACK")
                raise

        return StoreApplyReceipt(
            ok=True,
            txn_id=txn_id,
            backend=self.backend,
            target=self.target,
            patch_plan_sha256=plan.sha256(),
            post_state_sha256=post_sha256,
            reason=f"Applied {len(plan.operations)} DuckDB operation(s).",
        )

    def revert_transaction(self, transaction: RepairTransaction, *, log_path: Path) -> None:
        """Execute rollback SQL for a recorded DuckDB table-store transaction."""
        if transaction.patch_plan is None:
            raise TableStoreError("Table-store transaction is missing its patch plan.")
        plan = PatchPlan.model_validate(transaction.patch_plan)
        if plan.backend != self.backend:
            raise TableStoreError(f"Patch plan backend {plan.backend!r} does not match DuckDB.")
        with self._connect(read_only=False) as connection:
            try:
                connection.execute("BEGIN TRANSACTION")
                for sql in reversed(plan.rollback_sql):
                    connection.execute(sql)
                connection.execute("COMMIT")
                append_reverted_event(log_path, transaction.txn_id)
            except Exception:
                connection.execute("ROLLBACK")
                raise


def load_duckdb_transaction(log_path: Path) -> tuple[DuckDBStore, RepairTransaction]:
    """Load a DuckDB table-store transaction and recreate its store."""
    transaction = load_transaction(log_path)
    if transaction.patch_plan is None:
        raise TableStoreError("Transaction is missing a patch plan.")
    plan = PatchPlan.model_validate(transaction.patch_plan)
    database = plan.audit_metadata.get("database")
    if not database:
        raise TableStoreError("DuckDB transaction is missing database metadata.")
    return (
        DuckDBStore(
            database_path=Path(database),
            relation=plan.relation,
            row_identity_columns=plan.row_identity_columns,
            target=plan.target,
        ),
        transaction,
    )