from __future__ import annotations

import json
from datetime import date
from pathlib import Path

from app.models.event_preset import EventPreset, EventScenarioOverrides

DEFAULT_EVENT_PRESET_FILE = Path(__file__).resolve().parents[2] / "config" / "event_presets.json"


def default_event_presets() -> list[EventPreset]:
    return [
        EventPreset(
            event_preset_id="gld-jan-2024-selloff-v1",
            slug="gld-jan-2024-selloff",
            display_name="GLD January 2024 Selloff",
            symbol="GLD",
            window_start=date(2024, 1, 2),
            window_end=date(2024, 1, 8),
            anchor_date=date(2024, 1, 4),
            event_type="selloff",
            tags=("system", "selloff", "macro"),
            description="Short January 2024 selloff window for deterministic synthetic event comparisons.",
            scenario_overrides=EventScenarioOverrides(
                default_template_slugs=(
                    "protective-put-atm-12m",
                    "protective-put-95pct-12m",
                    "protective-put-90pct-12m",
                    "ladder-50-50-atm-95pct-12m",
                )
            ),
        ),
        EventPreset(
            event_preset_id="gld-jan-2024-drawdown-v1",
            slug="gld-jan-2024-drawdown",
            display_name="GLD January 2024 Drawdown",
            symbol="GLD",
            window_start=date(2024, 1, 2),
            window_end=date(2024, 1, 8),
            anchor_date=date(2024, 1, 5),
            event_type="selloff",
            tags=("system", "drawdown"),
            description="January 2024 drawdown preset for deterministic synthetic event comparison runs.",
            scenario_overrides=EventScenarioOverrides(
                lookback_days=0,
                recovery_days=0,
                default_template_slugs=(
                    "protective-put-atm-12m",
                    "ladder-50-50-atm-95pct-12m",
                    "ladder-33-33-33-atm-95pct-90pct-12m",
                ),
            ),
        ),
        EventPreset(
            event_preset_id="gld-jan-2024-stress-window-v1",
            slug="gld-jan-2024-stress-window",
            display_name="GLD January 2024 Stress Window",
            symbol="GLD",
            window_start=date(2024, 1, 2),
            window_end=date(2024, 1, 8),
            anchor_date=None,
            event_type="stress_test",
            tags=("system", "stress_test"),
            description="Stress-window preset with a modest warmup and recovery tail for report scaffolding.",
            scenario_overrides=EventScenarioOverrides(
                lookback_days=0,
                recovery_days=0,
                default_template_slugs=(
                    "protective-put-atm-12m",
                    "protective-put-95pct-12m",
                ),
            ),
        ),
    ]


class FileEventPresetRepository:
    def __init__(self, path: str | Path = DEFAULT_EVENT_PRESET_FILE) -> None:
        self.path = Path(path)

    def list_presets(self) -> list[EventPreset]:
        self._ensure_seeded()
        payload = json.loads(self.path.read_text())
        return [EventPreset.from_dict(item) for item in payload.get("presets", [])]

    def get_by_slug(self, slug: str) -> EventPreset | None:
        return next((preset for preset in self.list_presets() if preset.slug == slug), None)

    def save_all(self, presets: list[EventPreset]) -> None:
        self.path.parent.mkdir(parents=True, exist_ok=True)
        payload = {"presets": [preset.to_dict() for preset in presets]}
        self.path.write_text(json.dumps(payload, indent=2) + "\n")

    def _ensure_seeded(self) -> None:
        if self.path.exists():
            return
        self.save_all(default_event_presets())


class EventPresetService:
    def __init__(self, repository: FileEventPresetRepository | None = None) -> None:
        self.repository = repository or FileEventPresetRepository()

    def list_presets(self, symbol: str | None = None) -> list[EventPreset]:
        presets = self.repository.list_presets()
        if symbol is None:
            return presets
        normalized_symbol = symbol.strip().upper()
        return [preset for preset in presets if preset.symbol.strip().upper() == normalized_symbol]

    def get_preset(self, slug: str) -> EventPreset:
        preset = self.repository.get_by_slug(slug)
        if preset is None:
            raise KeyError(f"Unknown event preset: {slug}")
        return preset