"""
Core domain models for activity-core.
"""

from __future__ import annotations

import json
from typing import Annotated, Any, Literal, Union
from datetime import datetime
from uuid import UUID

from pydantic import BaseModel, Field


# ── EventEnvelope (T40) ───────────────────────────────────────────────────────

class EventEnvelope(BaseModel):
    """Standard internal event envelope. All inbound events (NATS, webhook, cron)
    are normalised into this shape before processing."""

    id: str = Field(description="UUID v4 — stable unique ID for deduplication.")
    type: str = Field(description="Dot-namespaced event type, e.g. 'org.repo.registered'.")
    version: str = Field(default="1.0", description="Schema version string.")
    timestamp: datetime = Field(description="When the event occurred (UTC).")
    publisher: str = Field(description="Originating service, e.g. 'the-custodian/state-hub'.")
    attributes: dict[str, Any] = Field(
        default_factory=dict,
        description="Event-specific attributes; structure varies by event type.",
    )

    @classmethod
    def from_nats_message(cls, msg: Any) -> "EventEnvelope":
        """Decode a NATS JetStream message into an EventEnvelope."""
        raw = json.loads(msg.data.decode())
        return cls.model_validate(raw)

    @classmethod
    def from_webhook_payload(cls, source: str, payload: dict) -> "EventEnvelope":
        """Build an EventEnvelope from a raw webhook payload (pre-normalised)."""
        return cls.model_validate(payload)


# ── Trigger configs ───────────────────────────────────────────────────────────

class CronTriggerConfig(BaseModel):
    trigger_type: Literal["cron"] = "cron"
    cron_expression: str = Field(
        description="Standard 5-field cron expression, e.g. '0 9 * * 1-5'."
    )
    timezone: str = Field(default="UTC", description="IANA timezone name.")
    jitter_seconds: int = Field(default=0, ge=0)
    misfire_policy: Literal["skip", "catchup", "compress"] = Field(default="skip")


class EventTriggerConfig(BaseModel):
    trigger_type: Literal["event"] = "event"
    event_type: str = Field(
        description="Matches EventEnvelope.type. Router fires this activity on match."
    )
    filters: dict[str, Any] = Field(
        default_factory=dict,
        description="All filters must match EventEnvelope.attributes for routing.",
    )


class ScheduledTriggerConfig(BaseModel):
    """One-off future trigger that fires once at a specified UTC datetime."""

    trigger_type: Literal["scheduled"] = "scheduled"
    at: datetime = Field(description="UTC datetime when the workflow should be triggered.")
    timezone: str = Field(default="UTC", description="IANA timezone name (informational).")


TriggerConfig = Annotated[
    Union[CronTriggerConfig, EventTriggerConfig, ScheduledTriggerConfig],
    Field(discriminator="trigger_type"),
]


# ── Rules and instructions (T34) ──────────────────────────────────────────────

class ActionDef(BaseModel):
    task_template: str = Field(description="Path to task template .md, relative to repo root.")
    target_repo: str | None = Field(
        default=None,
        description="Attribute-access expression or literal repo slug.",
    )
    priority: str = Field(default="medium")
    labels: list[str] = Field(default_factory=list)
    due_in_days: int | None = Field(default=None)


class RuleDef(BaseModel):
    id: str
    condition: str = Field(
        default="",
        description="Rule DSL expression; empty string means always true.",
    )
    action: ActionDef


class InstructionDef(BaseModel):
    id: str
    condition: str = Field(
        default="",
        description="Optional pre-filter using Rule DSL; empty means always execute.",
    )
    trusted_fields: list[str] = Field(
        description="Allowlist of event/context fields that may appear in the prompt template.",
    )
    model: str = Field(description="LLM model identifier, e.g. 'claude-sonnet-4-6'.")
    prompt: str = Field(description="Prompt template with {field.path} placeholders.")
    output_schema: str = Field(description="Path to JSON Schema file for output validation.")
    review_required: bool = Field(default=False)


# ── Context sources ───────────────────────────────────────────────────────────

class ContextSource(BaseModel):
    """One external data source that the workflow queries to build the context snapshot."""

    name: str = Field(description="Logical name; referenced as 'context.<name>' in templates.")
    type: str = Field(description="Source adapter type: 'repo-scoping' | 'state-hub' | etc.")
    query: str = Field(default="", description="Named query to execute against the source.")
    params: dict[str, Any] = Field(default_factory=dict)
    bind_to: str = Field(default="", description="Context key to bind the result to.")


# ── Task templates (legacy) ───────────────────────────────────────────────────

class TaskTemplate(BaseModel):
    """Legacy task template — ignored when ActivityDefinition.rules is non-empty."""

    task_type: str
    condition: str | None = None
    params_template: dict[str, Any] = Field(default_factory=dict)


# ── ActivityDefinition ────────────────────────────────────────────────────────

class ActivityDefinition(BaseModel):
    """Versioned definition: trigger + context sources + rules/instructions."""

    id: UUID
    name: str
    enabled: bool = True
    trigger_config: TriggerConfig
    context_sources: list[ContextSource] = Field(default_factory=list)
    # New rule/instruction pipeline (T34)
    rules: list[RuleDef] = Field(default_factory=list)
    instructions: list[InstructionDef] = Field(default_factory=list)
    # Legacy — ignored when rules is non-empty
    task_templates: list[TaskTemplate] = Field(default_factory=list)
    dedupe_key_strategy: Literal["skip", "catchup", "compress"] = Field(default="skip")
    version: int = Field(default=1, ge=1)
    status: str = Field(default="active")