from __future__ import annotations

from dataclasses import dataclass, field

from .models import KnowledgeArtifact


@dataclass(frozen=True)
class RelationshipEdge:
    source: str
    target: str
    type: str


@dataclass(frozen=True)
class RelationshipSummary:
    nodes: list[str]
    edges: list[RelationshipEdge]
    relationship_types: dict[str, int] = field(default_factory=dict)

    @property
    def node_count(self) -> int:
        return len(self.nodes)

    @property
    def edge_count(self) -> int:
        return len(self.edges)


def relationship_summary(artifacts: list[KnowledgeArtifact]) -> RelationshipSummary:
    ids = {artifact.id for artifact in artifacts}
    edges: list[RelationshipEdge] = []
    type_counts: dict[str, int] = {}
    for artifact in artifacts:
        for relationship in artifact.relationships:
            target = relationship.get("target")
            relation_type = str(relationship.get("type") or "related")
            if isinstance(target, str) and target in ids:
                edges.append(RelationshipEdge(artifact.id, target, relation_type))
                type_counts[relation_type] = type_counts.get(relation_type, 0) + 1
    return RelationshipSummary(
        nodes=sorted(ids),
        edges=edges,
        relationship_types=dict(sorted(type_counts.items())),
    )


def export_mermaid(summary: RelationshipSummary) -> str:
    lines = ["graph TD"]
    for node in summary.nodes:
        lines.append(f"  {node}")
    for edge in summary.edges:
        lines.append(f"  {edge.source} -->|{edge.type}| {edge.target}")
    return "\n".join(lines) + "\n"