"""Artifact — the heart of the "Everything is an Artifact" principle.

One single generic model captures every lifecycle entity (requirement,
task, commit, test, deployment, incident, ...). Artifact subtypes are
expressed via the ``type`` enum / string and stored in the same MongoDB
``artifacts`` collection.

Relationships between artifacts live in ``artifact_relationships``
collection and are modelled as explicit directed edges — this keeps the
option open to project the same data onto a graph database later without
rewriting domain logic.
"""

from __future__ import annotations

from typing import Any, Optional, List, Dict
from enum import Enum

from pydantic import Field

from asf_domain.base import (
    ASFBaseModel,
    TenantScopedModel,
    ASFFieldID,
    UTCDatetime,
    ArtifactType,
    RelationshipType,
    generate_id,
)


# ======================================================================
# Artifact itself
# ======================================================================


class ArtifactBase(ASFBaseModel):
    type: ArtifactType = Field(
        ..., description="Kind of artifact (requirement | task | commit | …)"
    )
    external_id: Optional[str] = Field(
        None,
        max_length=255,
        description="Optional identifier in an external system "
        "(e.g. GitHub PR id, Jira issue key)",
    )
    title: str = Field(..., min_length=1, max_length=500)
    content: Optional[str] = Field(
        None,
        description="Primary human readable body (markdown, description, diff, log body, …). "
        "Large content should live in MinIO; store a reference here or in metadata.",
    )
    source: Optional[str] = Field(
        None,
        max_length=255,
        description="Origin system: jira, github, manual, ai, …",
    )
    status: Optional[str] = Field(
        None, max_length=80, description="Status (e.g. open, done, failed, released)."
    )


class ArtifactCreate(ArtifactBase):
    """Create payload. ``tenant_id`` and ``project_id`` are set server-side."""

    project_id: ASFFieldID = Field(
        ..., description="Owning project (validated against tenant context server side)."
    )
    metadata: Dict[str, Any] = Field(
        default_factory=dict,
        description="Arbitrary extensible fields. Use this for artifact subtype "
        "specific attributes (e.g. commit.sha, test.outcome, deployment.env).",
    )


class ArtifactUpdate(ASFBaseModel):
    title: Optional[str] = Field(None, min_length=1, max_length=500)
    content: Optional[str] = None
    type: Optional[ArtifactType] = None
    external_id: Optional[str] = None
    source: Optional[str] = None
    status: Optional[str] = None
    metadata: Optional[Dict[str, Any]] = Field(
        None,
        description="When provided, performs a shallow merge with existing metadata.",
    )


class Artifact(TenantScopedModel, ArtifactBase):
    """Stored Artifact record.

    ``relationships`` is a denormalised, always-stale list kept for fast
    reads in the UI. The authoritative source of truth for edges is the
    ``artifact_relationships`` collection.
    """

    id: ASFFieldID = Field(default_factory=generate_id)
    project_id: ASFFieldID = ...
    version: int = Field(
        1, ge=1, description="Monotonic version bumped on every update."
    )
    metadata: Dict[str, Any] = Field(default_factory=dict)
    created_at: UTCDatetime = ...
    updated_at: UTCDatetime = ...
    created_by: Optional[ASFFieldID] = Field(
        None, description="User id that created this artifact (null = system / import)."
    )


# ======================================================================
# ArtifactRelationship — the explicit edge
# ======================================================================


class RelationshipDirection(str, Enum):
    FORWARD = "forward"
    REVERSE = "reverse"


class ArtifactRelationshipBase(ASFBaseModel):
    relationship_type: RelationshipType = Field(
        ...,
        description="Semantic predicate: ``source <relationship_type> target``.",
    )
    source_artifact_id: ASFFieldID = Field(
        ..., description="Source artifact id (subject)."
    )
    target_artifact_id: ASFFieldID = Field(
        ..., description="Target artifact id (object)."
    )
    metadata: Dict[str, Any] = Field(
        default_factory=dict,
        description="Free-form metadata on the edge (confidence, evidence ref, …).",
    )


class ArtifactRelationshipCreate(ArtifactRelationshipBase):
    """Create payload. tenant_id / project_ids are validated server side."""
    pass


class ArtifactRelationship(TenantScopedModel, ArtifactRelationshipBase):
    """Stored edge between two artifacts.

    Invariant: both source and target MUST belong to the same tenant.
    They MAY live in different projects inside that tenant when an
    explicit cross-project reference is intentional.
    """

    id: ASFFieldID = Field(default_factory=generate_id)
    source_project_id: ASFFieldID = ...
    target_project_id: ASFFieldID = ...
    created_at: UTCDatetime = ...
    updated_at: UTCDatetime = ...