feat: add export filters for projects and scenarios with filtering capabilities

services/export_serializers.py

@@ -0,0 +1,178 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import timezone
+from functools import partial
+from typing import Callable, Iterable, Iterator, Sequence
+
+from .export_query import ProjectExportFilters, ScenarioExportFilters
+
+__all__ = [
+    "CSVExportColumn",
+    "CSVExportRowFactory",
+    "build_project_row_factory",
+    "build_scenario_row_factory",
+]
+
+CSVValueFormatter = Callable[[object | None], str]
+RowExtractor = Callable[[object], Sequence[object | None]]
+
+
+@dataclass(slots=True, frozen=True)
+class CSVExportColumn:
+    """Describe how a field is rendered into CSV output."""
+
+    header: str
+    accessor: str
+    formatter: CSVValueFormatter | None = None
+
+
+@dataclass(slots=True, frozen=True)
+class CSVExportRowFactory:
+    """Builds row values for CSV serialization."""
+
+    columns: tuple[CSVExportColumn, ...]
+
+    def headers(self) -> tuple[str, ...]:
+        return tuple(column.header for column in self.columns)
+
+    def to_row(self, entity: object) -> tuple[str, ...]:
+        values: list[str] = []
+        for column in self.columns:
+            value = getattr(entity, column.accessor, None)
+            formatter = column.formatter or _default_formatter
+            values.append(formatter(value))
+        return tuple(values)
+
+
+def build_project_row_factory(
+    *,
+    include_timestamps: bool = True,
+    include_description: bool = True,
+) -> CSVExportRowFactory:
+    columns: list[CSVExportColumn] = [
+        CSVExportColumn(header="name", accessor="name"),
+        CSVExportColumn(header="location", accessor="location"),
+        CSVExportColumn(header="operation_type", accessor="operation_type"),
+    ]
+    if include_description:
+        columns.append(
+            CSVExportColumn(header="description", accessor="description")
+        )
+    if include_timestamps:
+        columns.extend(
+            (
+                CSVExportColumn(
+                    header="created_at",
+                    accessor="created_at",
+                    formatter=_format_datetime,
+                ),
+                CSVExportColumn(
+                    header="updated_at",
+                    accessor="updated_at",
+                    formatter=_format_datetime,
+                ),
+            )
+        )
+    return CSVExportRowFactory(columns=tuple(columns))
+
+
+def build_scenario_row_factory(
+    *,
+    include_description: bool = True,
+    include_timestamps: bool = True,
+) -> CSVExportRowFactory:
+    columns: list[CSVExportColumn] = [
+        CSVExportColumn(header="project_name", accessor="project_name"),
+        CSVExportColumn(header="name", accessor="name"),
+        CSVExportColumn(header="status", accessor="status"),
+        CSVExportColumn(
+            header="start_date",
+            accessor="start_date",
+            formatter=_format_date,
+        ),
+        CSVExportColumn(
+            header="end_date",
+            accessor="end_date",
+            formatter=_format_date,
+        ),
+        CSVExportColumn(header="discount_rate",
+                        accessor="discount_rate", formatter=_format_number),
+        CSVExportColumn(header="currency", accessor="currency"),
+        CSVExportColumn(header="primary_resource",
+                        accessor="primary_resource"),
+    ]
+    if include_description:
+        columns.append(
+            CSVExportColumn(header="description", accessor="description")
+        )
+    if include_timestamps:
+        columns.extend(
+            (
+                CSVExportColumn(
+                    header="created_at",
+                    accessor="created_at",
+                    formatter=_format_datetime,
+                ),
+                CSVExportColumn(
+                    header="updated_at",
+                    accessor="updated_at",
+                    formatter=_format_datetime,
+                ),
+            )
+        )
+    return CSVExportRowFactory(columns=tuple(columns))
+
+
+def stream_projects_to_csv(
+    projects: Sequence[object],
+    *,
+    row_factory: CSVExportRowFactory | None = None,
+) -> Iterator[str]:
+    factory = row_factory or build_project_row_factory()
+    yield _join_row(factory.headers())
+    for project in projects:
+        yield _join_row(factory.to_row(project))
+
+
+def stream_scenarios_to_csv(
+    scenarios: Sequence[object],
+    *,
+    row_factory: CSVExportRowFactory | None = None,
+) -> Iterator[str]:
+    factory = row_factory or build_scenario_row_factory()
+    yield _join_row(factory.headers())
+    for scenario in scenarios:
+        yield _join_row(factory.to_row(scenario))
+
+
+def _join_row(values: Iterable[str]) -> str:
+    return ",".join(values)
+
+
+def _default_formatter(value: object | None) -> str:
+    if value is None:
+        return ""
+    return str(value)
+
+
+def _format_datetime(value: object | None) -> str:
+    from datetime import datetime
+
+    if not isinstance(value, datetime):
+        return ""
+    return value.astimezone(timezone.utc).replace(tzinfo=timezone.utc).isoformat().replace("+00:00", "Z")
+
+
+def _format_date(value: object | None) -> str:
+    from datetime import date
+
+    if not isinstance(value, date):
+        return ""
+    return value.isoformat()
+
+
+def _format_number(value: object | None) -> str:
+    if value is None:
+        return ""
+    return f"{value:.2f}"