"""Canonical page content and links shared by retrieval, scoring, and citations."""
from pathlib import Path

from .config import get_settings
from .models import KnowledgeDocument, KnowledgePage


def text_url(document_id: int, page: int) -> str:
    return f"/api/knowledge/documents/{document_id}/pages/{page}"


def image_url(document_id: int, page: int) -> str:
    return f"{text_url(document_id, page)}/image"


def page_text(source: dict) -> str:
    blocks = [str(source.get("text") or "").strip()]
    blocks.extend("表格: " + str(table.get("rows", table)) for table in source.get("tables", []))
    return "\n".join(block for block in blocks if block)


def relative_image_path(value: str | None) -> str | None:
    if not value:
        return None
    root = get_settings().processed_path.resolve()
    path = Path(value).resolve()
    if not path.is_relative_to(root):
        raise ValueError("页面图像路径不在处理目录内")
    return str(path.relative_to(root))


def page_image_path(db, doc: KnowledgeDocument, page: int) -> Path | None:
    root = get_settings().processed_path.resolve()
    record = db.get(KnowledgePage, (doc.id, page))
    path = (root / record.image_path).resolve() if record and record.image_path else None
    return path if path and path.is_relative_to(root) and path.is_file() else None


def page_links(db, document_id: int | None, page: int | None) -> dict:
    """Stable citation links plus the page type, so callers can label the source."""
    empty = {"url": None, "image_url": None, "page_type": None, "section": None}
    if not document_id or not page:
        return empty
    doc = db.get(KnowledgeDocument, document_id)
    if not doc:
        return empty
    record = db.get(KnowledgePage, (document_id, page))
    if not record:
        return empty
    return {"url": text_url(document_id, page),
            "image_url": image_url(document_id, page) if page_image_path(db, doc, page) else None,
            "page_type": record.page_type or "unknown",
            "section": record.section or ""}


def evidence_links(db, evidence) -> dict:
    return page_links(db, evidence.document_id, evidence.page)


def page_types(db, document_ids) -> dict[int, str]:
    """Page type per page of the given documents, for labelling citations in bulk."""
    from sqlalchemy import select as _select
    ids = [item for item in dict.fromkeys(document_ids or []) if item]
    if not ids:
        return {}
    rows = db.execute(_select(KnowledgePage.document_id, KnowledgePage.page, KnowledgePage.page_type)
                      .where(KnowledgePage.document_id.in_(ids))).all()
    return {(document_id, page): (page_type or "unknown") for document_id, page, page_type in rows}