from __future__ import annotations

import json
import re
import uuid
from datetime import date as date_cls
from datetime import datetime

from flask import Blueprint, g, jsonify, request

from . import cospend_client, llm_client, nc_client
from .auth import enforce_login
from .config import Config
from .db import get_conn

bp = Blueprint("api", __name__)
# Every route on this blueprint requires a valid session by default - a
# route added here later is protected automatically, not only if someone
# remembers to decorate it. (auth_routes.py's /auth/* blueprint is
# deliberately separate and unguarded - it's the login mechanism itself.)
bp.before_request(enforce_login)


@bp.get("/me")
def me():
    return jsonify(nc_user_id=g.nc_user_id)


# ---------------------------------------------------------------- receipts

@bp.post("/receipts")
def create_receipt():
    """multipart/form-data with an `image` file. Extracts items via LLM."""
    file = request.files.get("image")
    if file is None:
        return jsonify(error="missing 'image' file"), 400

    image_bytes = file.read()
    receipt_id = str(uuid.uuid4())
    image_path = f"{Config.UPLOAD_DIR}/{receipt_id}.jpg"
    with open(image_path, "wb") as f:
        f.write(image_bytes)

    try:
        extracted = llm_client.extract_receipt(image_bytes, mime_type=file.mimetype or "image/jpeg")
    except Exception as exc:  # noqa: BLE001 - surfaced to the client as-is
        return jsonify(error=f"extraction failed: {exc}"), 502

    items = extracted["items"]
    store_name = extracted["store_name"]
    # Fall back to today if the receipt's date wasn't readable - the user
    # can still override it in the review step.
    receipt_date = extracted["date"] or date_cls.today().isoformat()

    with get_conn() as conn:
        conn.execute(
            """INSERT INTO receipts (id, owner_nc_user_id, image_path, items_json, store_name, receipt_date)
               VALUES (?, ?, ?, ?, ?, ?)""",
            (receipt_id, g.nc_user_id, image_path, json.dumps(items), store_name, receipt_date),
        )

    return jsonify(id=receipt_id, items=items, store_name=store_name, date=receipt_date), 201


@bp.get("/receipts/<receipt_id>")
def get_receipt(receipt_id: str):
    receipt = _load_receipt(receipt_id, g.nc_user_id)
    if receipt is None:
        return jsonify(error="not found"), 404
    return jsonify(receipt)


@bp.patch("/receipts/<receipt_id>/items")
def update_items(receipt_id: str):
    """Body: {"items": [...]} — full replacement, for the review/edit step."""
    body = request.get_json(force=True) or {}
    items = body.get("items")
    if not isinstance(items, list):
        return jsonify(error="'items' must be a list"), 400

    with get_conn() as conn:
        cur = conn.execute(
            "UPDATE receipts SET items_json = ? WHERE id = ? AND owner_nc_user_id = ?",
            (json.dumps(items), receipt_id, g.nc_user_id),
        )
        if cur.rowcount == 0:
            return jsonify(error="not found"), 404

    return jsonify(id=receipt_id, items=items)


@bp.patch("/receipts/<receipt_id>/meta")
def update_meta(receipt_id: str):
    """Body: {"store_name"?: str, "date"?: "YYYY-MM-DD"} - user override for
    what the receipt reader guessed (or didn't find)."""
    body = request.get_json(force=True) or {}
    fields, values = [], []
    if "store_name" in body:
        fields.append("store_name = ?")
        values.append(body["store_name"])
    if "date" in body:
        if not re.match(r"^\d{4}-\d{2}-\d{2}$", str(body["date"] or "")):
            return jsonify(error="date must be YYYY-MM-DD"), 400
        fields.append("receipt_date = ?")
        values.append(body["date"])
    if not fields:
        return jsonify(error="nothing to update"), 400

    values.extend([receipt_id, g.nc_user_id])
    with get_conn() as conn:
        cur = conn.execute(
            f"UPDATE receipts SET {', '.join(fields)} WHERE id = ? AND owner_nc_user_id = ?", values
        )
        if cur.rowcount == 0:
            return jsonify(error="not found"), 404

    receipt = _load_receipt(receipt_id, g.nc_user_id)
    return jsonify(receipt)


def _load_receipt(receipt_id: str, owner_nc_user_id: str) -> dict | None:
    with get_conn() as conn:
        row = conn.execute(
            "SELECT * FROM receipts WHERE id = ? AND owner_nc_user_id = ?",
            (receipt_id, owner_nc_user_id),
        ).fetchone()
    if row is None:
        return None
    return {
        "id": row["id"],
        "items": json.loads(row["items_json"]),
        "store_name": row["store_name"],
        "date": row["receipt_date"],
        "status": row["status"],
        "created_at": row["created_at"],
    }


# -------------------------------------------------------------- cospend

@bp.get("/cospend/projects")
def cospend_projects():
    try:
        projects = cospend_client.get_projects(g.nc_user_id, g.nc_app_password)
    except Exception as exc:  # noqa: BLE001
        return jsonify(error=f"cospend request failed: {exc}"), 502
    return jsonify(projects=projects, default_project_id=Config.COSPEND_DEFAULT_PROJECT_ID or None)


@bp.get("/cospend/projects/<project_id>/members")
def cospend_members(project_id: str):
    try:
        members = cospend_client.get_members(g.nc_user_id, g.nc_app_password, project_id)
    except Exception as exc:  # noqa: BLE001
        return jsonify(error=f"cospend request failed: {exc}"), 502
    return jsonify(members)


# ------------------------------------------------------------------ groups

@bp.post("/receipts/<receipt_id>/groups")
def create_group(receipt_id: str):
    """Body: {cospend_project_id, payer_member_id, member_ids: [...], item_ids: [...]}

    No user-facing "name" - the group is fully described by the project +
    who's in the split, which is already what payer/member_ids capture.
    """
    receipt = _load_receipt(receipt_id, g.nc_user_id)
    if receipt is None:
        return jsonify(error="not found"), 404

    body = request.get_json(force=True) or {}
    project_id = body.get("cospend_project_id")
    payer_member_id = body.get("payer_member_id")
    member_ids = body.get("member_ids") or []
    item_ids = body.get("item_ids") or []

    if not project_id or not payer_member_id or not member_ids or not item_ids:
        return (
            jsonify(
                error="cospend_project_id, payer_member_id, member_ids and item_ids are required"
            ),
            400,
        )

    group_id = str(uuid.uuid4())
    with get_conn() as conn:
        conn.execute(
            """INSERT INTO groups
               (id, receipt_id, cospend_project_id, payer_member_id,
                member_ids_json, item_ids_json)
               VALUES (?, ?, ?, ?, ?, ?)""",
            (
                group_id,
                receipt_id,
                project_id,
                payer_member_id,
                json.dumps(member_ids),
                json.dumps(item_ids),
            ),
        )
        conn.execute("UPDATE receipts SET status = 'grouped' WHERE id = ?", (receipt_id,))

    return jsonify(id=group_id), 201


@bp.get("/receipts/<receipt_id>/groups")
def list_groups(receipt_id: str):
    # Ownership check on the parent receipt is enough - a group can't exist
    # without a receipt row, and receipts are already scoped per-owner.
    if _load_receipt(receipt_id, g.nc_user_id) is None:
        return jsonify(error="not found"), 404
    with get_conn() as conn:
        rows = conn.execute(
            "SELECT * FROM groups WHERE receipt_id = ? ORDER BY created_at", (receipt_id,)
        ).fetchall()
    return jsonify([_group_dict(r) for r in rows])


def _group_dict(row) -> dict:
    return {
        "id": row["id"],
        "receipt_id": row["receipt_id"],
        "cospend_project_id": row["cospend_project_id"],
        "payer_member_id": row["payer_member_id"],
        "member_ids": json.loads(row["member_ids_json"]),
        "item_ids": json.loads(row["item_ids_json"]),
        "status": row["status"],
        "share_url": row["share_url"],
        "cospend_bill_id": row["cospend_bill_id"],
        "error": row["error"],
    }


@bp.post("/receipts/<receipt_id>/groups/<group_id>/submit")
def submit_group(receipt_id: str, group_id: str):
    """Uploads the receipt photo to NC, shares it, creates the Cospend bill."""
    receipt = _load_receipt(receipt_id, g.nc_user_id)
    if receipt is None:
        return jsonify(error="receipt not found"), 404

    with get_conn() as conn:
        row = conn.execute(
            "SELECT * FROM groups WHERE id = ? AND receipt_id = ?", (group_id, receipt_id)
        ).fetchone()
    if row is None:
        return jsonify(error="group not found"), 404
    group = _group_dict(row)

    items_by_id = {item["id"]: item for item in receipt["items"]}
    selected = [items_by_id[i] for i in group["item_ids"] if i in items_by_id]
    if not selected:
        return jsonify(error="no matching items on this receipt"), 400

    total = round(sum(item["price"] for item in selected), 2)

    with open(_receipt_image_path(receipt_id, g.nc_user_id), "rb") as f:
        original_bytes = f.read()

    try:
        # Members list is fetched here (not stored at group-creation time) so
        # the label always reflects real names - also gives us the payer's
        # name for a slightly more readable title.
        members = cospend_client.get_members(
            g.nc_user_id, g.nc_app_password, group["cospend_project_id"]
        )
        names_by_id = {str(m["id"]): m["name"] for m in members}
        # member ids come back from Cospend as JSON numbers, not strings, and
        # may have round-tripped through JS (which doesn't distinguish) - str()
        # everything here so a missed match can't leave a raw int in the list
        # `join` chokes on.
        ower_names = [names_by_id.get(str(m), str(m)) for m in group["member_ids"]]
        members_label = " + ".join(ower_names) if ower_names else "split"

        # No highlighting - LLM-provided bounding boxes were unreliable
        # enough on real receipts to not be worth it. Just upload the
        # original photo, into the submitting user's own NC files.
        # Timestamp for human sorting/browsing in NC, group id suffix so two
        # submits in the same second (or a retry) never collide/overwrite.
        safe_label = re.sub(r"[^A-Za-z0-9_-]+", "-", members_label).strip("-") or "group"
        filename = f"{datetime.now():%Y-%m-%d_%H%M%S}_{safe_label}_{group_id[:8]}.jpg"
        rel_path = nc_client.upload_file(
            g.nc_user_id, g.nc_app_password, filename, original_bytes
        )
        share_url = nc_client.create_public_share(g.nc_user_id, g.nc_app_password, rel_path)

        item_lines = "\n".join(f"- {i['label']}: {i['price']}" for i in selected)

        # Descriptive title: store name when we have one, else fall back to
        # who's splitting it - either way followed by the share link, since
        # Cospend's UI only recognizes a bill as having an attachment when
        # the link is in `what` (the title); a link in `comment` is just
        # plain text and isn't picked up.
        # Only mention who it's split with when there's more than one bill
        # off this receipt to tell apart - with a single bill it's just
        # noise (the split is already visible in the bill itself).
        with get_conn() as conn:
            (bill_count,) = conn.execute(
                "SELECT COUNT(*) FROM groups WHERE receipt_id = ?", (receipt_id,)
            ).fetchone()
        store_name = receipt.get("store_name")
        if bill_count > 1:
            label = f"{store_name} ({members_label})" if store_name else members_label
        else:
            label = store_name or "receipt"
        bill_date = receipt.get("date") or date_cls.today().isoformat()

        bill_id = cospend_client.create_bill(
            g.nc_user_id,
            g.nc_app_password,
            project_id=group["cospend_project_id"],
            what=f"{label} {share_url}",
            amount=total,
            payer_id=int(group["payer_member_id"]),
            ower_ids=[int(m) for m in group["member_ids"]],
            date=bill_date,
            comment=item_lines,
        )
    except Exception as exc:  # noqa: BLE001
        with get_conn() as conn:
            conn.execute(
                "UPDATE groups SET status = 'failed', error = ? WHERE id = ?",
                (str(exc), group_id),
            )
        return jsonify(error=f"submit failed: {exc}"), 502

    with get_conn() as conn:
        conn.execute(
            """UPDATE groups SET status = 'submitted', share_url = ?, cospend_bill_id = ?
               WHERE id = ?""",
            (share_url, str(bill_id), group_id),
        )

    return jsonify(share_url=share_url, bill_id=bill_id, amount=total)


def _receipt_image_path(receipt_id: str, owner_nc_user_id: str) -> str:
    with get_conn() as conn:
        row = conn.execute(
            "SELECT image_path FROM receipts WHERE id = ? AND owner_nc_user_id = ?",
            (receipt_id, owner_nc_user_id),
        ).fetchone()
    return row["image_path"]