from __future__ import annotations

import re
from pathlib import Path
from typing import Any, Iterable

from app.modules.documents.services import client_folder_parts, get_active_storage_node_for_branch, sanitize_segment


def _join_local_path(root: str, relative: str) -> str:
    root = (root or "").strip().rstrip("\\/")
    if not root:
        return ""
    if re.match(r"^[A-Za-z]:", root) or "\\" in root:
        return root + "\\" + relative.replace("/", "\\")
    return root + "/" + relative.lstrip("/")


def build_engagement_resource_context(db, engagement, tasks: Iterable[Any], documents: Iterable[Any]) -> dict[str, Any]:
    """Presentation-only engagement resource data using existing storage/task models.

    No new persistence is introduced here. Accounting paths follow the same FY/client
    folder convention already used by the ERP Local Agent. Task-category uploads map
    to an existing task so evidence/AQMM/document controls remain authoritative.
    """
    tasks = list(tasks or [])
    documents = list(documents or [])
    client = getattr(engagement, "client", None)
    client_id = int(getattr(engagement, "client_id", 0) or 0)
    fy = str(getattr(engagement, "financial_year", "") or "").strip()

    accounting_relative_dir = ""
    accounting_relative_path = ""
    accounting_local_path = ""
    storage_root_path = ""
    storage_node_name = ""
    if client and client_id and fy:
        fy_folder = sanitize_segment(f"FY{fy}", "FY")
        letter, client_folder = client_folder_parts(client, client_id)
        relative_dir = Path(fy_folder) / "Clients" / letter / client_folder / "Accounting"
        accounting_relative_dir = relative_dir.as_posix()
        accounting_relative_path = (relative_dir / f"client_{client_id:08d}.act").as_posix()
        node = get_active_storage_node_for_branch(
            db,
            int(getattr(engagement, "tenant_id", 0) or 0),
            getattr(engagement, "branch_id", None),
        )
        if node:
            storage_root_path = str(getattr(node, "storage_root_path", "") or "").strip()
            storage_node_name = str(getattr(node, "node_name", "") or "").strip()
            accounting_local_path = _join_local_path(storage_root_path, accounting_relative_path)

    category_map: dict[str, int] = {}
    for task in tasks:
        category = str(getattr(task, "task_category", "") or "").strip() or "General Workflow"
        task_id = int(getattr(task, "id", 0) or 0)
        if task_id and category not in category_map:
            category_map[category] = task_id
    categories = [{"name": name, "task_id": task_id} for name, task_id in category_map.items()]

    document_options = []
    for doc in documents:
        versions = list(getattr(doc, "versions", None) or [])
        latest = versions[0] if versions else None
        document_options.append({
            "id": int(getattr(doc, "id", 0) or 0),
            "title": str(getattr(doc, "title", "") or "Document"),
            "document_type": str(getattr(doc, "document_type", "GENERAL") or "GENERAL"),
            "version_no": int(getattr(doc, "current_version_no", 0) or 0),
            "task_instance_id": getattr(doc, "task_instance_id", None),
            "latest_filename": str(getattr(latest, "original_filename", "") or "") if latest else "",
            "latest_relative_path": str(getattr(latest, "local_relative_path", "") or "") if latest else "",
            "storage_status": str(getattr(latest, "storage_status", "") or "") if latest else "",
        })

    return {
        "accounting_relative_dir": accounting_relative_dir,
        "accounting_relative_path": accounting_relative_path,
        "accounting_local_path": accounting_local_path,
        "storage_root_path": storage_root_path,
        "storage_node_name": storage_node_name,
        "task_categories": categories,
        "default_upload_task_id": categories[0]["task_id"] if categories else None,
        "document_options": document_options,
    }