"""UserHistory — normalised view of a user's feedback events for inference."""
from __future__ import annotations

from dataclasses import dataclass, field
from datetime import datetime, timezone


@dataclass
class FeedbackEvent:
    action: str              # 'done' | 'dismiss' | 'snooze' | 'helpful' | 'not_helpful'
    dwell_ms: int | None
    created_at: str          # ISO 8601

    @property
    def hour(self) -> int:
        """Hour of day (0-23) when the feedback was recorded."""
        try:
            dt = datetime.fromisoformat(self.created_at.replace("Z", "+00:00"))
        except ValueError:
            return 12
        if dt.tzinfo is None:
            dt = dt.replace(tzinfo=timezone.utc)
        return dt.hour


@dataclass
class TaskCompletion:
    """A completed task that had a due date — used for lateness inference."""
    project_id: str | None
    completed_at: str   # ISO 8601
    due_at: str         # ISO 8601

    @property
    def lateness_days(self) -> float:
        """Days between due_at and completed_at. Negative = completed early."""
        try:
            def _parse(s: str) -> datetime:
                dt = datetime.fromisoformat(s.replace("Z", "+00:00"))
                return dt if dt.tzinfo else dt.replace(tzinfo=timezone.utc)
            return (_parse(self.completed_at) - _parse(self.due_at)).total_seconds() / 86_400
        except ValueError:
            return 0.0


@dataclass
class UserHistory:
    user_id: str
    events: list[FeedbackEvent] = field(default_factory=list)
    task_completions: list[TaskCompletion] = field(default_factory=list)