from __future__ import annotations

from hashlib import sha256

from app.modules.rag.contracts import EvidenceLink, EvidenceType, RagDocument, RagLayer, RagSource
from app.modules.rag.indexing.docs.chunkers.markdown_chunker import SectionChunk


class DocsDocumentBuilder:
    def build_module_catalog(self, source: RagSource, frontmatter: dict, summary_text: str, doc_kind: str) -> RagDocument | None:
        module_id = str(frontmatter.get("id") or "").strip()
        module_type = str(frontmatter.get("type") or "").strip()
        domain = str(frontmatter.get("domain") or "").strip()
        if not module_id or not module_type or not domain:
            return None
        links = frontmatter.get("links") or {}
        metadata = {
            "module_id": module_id,
            "type": module_type,
            "domain": domain,
            "status": frontmatter.get("status"),
            "version": frontmatter.get("version"),
            "tags": frontmatter.get("tags") or [],
            "owners": frontmatter.get("owners") or [],
            "links": links,
            "source_path": source.path,
            "summary_text": summary_text[:4000],
            "doc_kind": doc_kind,
        }
        metadata.update({name: links.get(name, []) for name in (
            "calls_api", "called_by", "uses_logic", "used_by", "reads_db", "writes_db",
            "integrates_with", "emits_events", "consumes_events",
        )})
        return RagDocument(
            layer=RagLayer.DOCS_MODULE_CATALOG,
            source=source,
            title=module_id,
            text=summary_text[:4000] or module_id,
            metadata=metadata,
        )

    def build_section(self, source: RagSource, chunk: SectionChunk, frontmatter: dict, doc_kind: str) -> RagDocument:
        module_id = str(frontmatter.get("id") or source.path)
        metadata = {
            "module_id": module_id,
            "type": frontmatter.get("type"),
            "domain": frontmatter.get("domain"),
            "tags": frontmatter.get("tags") or [],
            "section_path": chunk.section_path,
            "section_title": chunk.section_title,
            "order": chunk.order,
            "doc_kind": doc_kind,
            "source_path": source.path,
            "artifact_type": "DOCS",
        }
        return RagDocument(
            layer=RagLayer.DOCS_SECTION_INDEX,
            source=source,
            title=f"{module_id}:{chunk.section_title}",
            text=chunk.content,
            metadata=metadata,
        )

    def build_policy(self, source: RagSource, frontmatter: dict, chunk: SectionChunk, doc_kind: str) -> RagDocument | None:
        policy_id = str(frontmatter.get("id") or "").strip()
        applies_to = frontmatter.get("applies_to") or frontmatter.get("type")
        if not policy_id:
            return None
        metadata = {
            "policy_id": policy_id,
            "applies_to": applies_to,
            "rules": chunk.content[:4000],
            "default_behaviors": frontmatter.get("default_behaviors") or [],
            "doc_kind": doc_kind,
            "section_path": chunk.section_path,
            "source_path": source.path,
        }
        return RagDocument(
            layer=RagLayer.DOCS_POLICY_INDEX,
            source=source,
            title=policy_id,
            text=chunk.content[:4000],
            metadata=metadata,
        )

    def build_fact(
        self,
        source: RagSource,
        *,
        subject_id: str,
        predicate: str,
        obj: str,
        object_ref: str | None,
        anchor: str,
        tags: list[str] | None = None,
    ) -> RagDocument:
        fact_id = sha256(f"{subject_id}|{predicate}|{obj}|{source.path}|{anchor}".encode("utf-8")).hexdigest()
        metadata = {
            "fact_id": fact_id,
            "subject_id": subject_id,
            "predicate": predicate,
            "object": obj,
            "object_ref": object_ref,
            "anchor": anchor,
            "tags": tags or [],
            "source_path": source.path,
        }
        return RagDocument(
            layer=RagLayer.DOCS_FACT_INDEX,
            source=source,
            title=f"{subject_id}:{predicate}",
            text=f"{subject_id} {predicate} {obj}".strip(),
            metadata=metadata,
            links=[EvidenceLink(type=EvidenceType.DOC_FACT, target_id=fact_id, path=source.path, note=anchor)],
        )