"""Export collections to Postman Collection v2.1 JSON."""
import json
from app.models import HttpRequest
from app.core import storage


def export_collection(collection_id: int) -> str:
    collections = storage.get_collections()
    col = next((c for c in collections if c["id"] == collection_id), None)
    if not col:
        raise ValueError(f"Collection {collection_id} not found")

    items = []

    def make_request_item(r: dict) -> dict:
        header = [{"key": k, "value": v} for k, v in r.get("headers", {}).items()]
        url_raw = r.get("url", "")
        params = r.get("params", {})
        query = [{"key": k, "value": v} for k, v in params.items()]

        body_obj = None
        body = r.get("body", "")
        body_type = r.get("body_type", "raw")
        if body:
            if body_type == "urlencoded":
                pairs = []
                for line in body.split("&"):
                    if "=" in line:
                        k, _, v = line.partition("=")
                        pairs.append({"key": k, "value": v})
                body_obj = {"mode": "urlencoded", "urlencoded": pairs}
            else:
                body_obj = {"mode": "raw", "raw": body}

        item = {
            "name": r.get("name") or url_raw,
            "request": {
                "method": r.get("method", "GET"),
                "header": header,
                "url": {"raw": url_raw, "query": query},
            }
        }
        if body_obj:
            item["request"]["body"] = body_obj
        return item

    # Top-level requests (no folder)
    for r in storage.get_requests(collection_id):
        items.append(make_request_item(r))

    # Folders
    for folder in storage.get_folders(collection_id):
        folder_item = {
            "name": folder["name"],
            "item": [make_request_item(r) for r in storage.get_requests(collection_id, folder["id"])]
        }
        items.append(folder_item)

    collection = {
        "info": {
            "name": col["name"],
            "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
        },
        "item": items
    }
    return json.dumps(collection, indent=2)