import json
import os
from decimal import Decimal

from shared.db import current_week, get_orders, get_roster, get_summary
from shared.slack import post_channel_message, send_dm


class DecimalEncoder(json.JSONEncoder):
    def default(self, o):
        if isinstance(o, Decimal):
            return float(o)
        return super().default(o)


def lambda_handler(event, context):
    event_type = event.get("event", "")

    if event_type == "menu_published":
        return handle_menu_published(event)
    elif event_type == "orders_aggregated":
        return handle_orders_aggregated(event)
    elif event_type == "reminder":
        return handle_reminder(event)
    elif event_type == "order_confirmed":
        return handle_order_confirmed(event)

    return {"error": f"Unknown event type: {event_type}"}


def handle_menu_published(event):
    form_url = os.environ.get("FORM_URL", "")
    week = event.get("week", current_week())
    meal_count = event.get("meal_count", "")

    text = "This week's meal order is open! Deadline: Thursday at 11:59pm."
    blocks = [
        {
            "type": "header",
            "text": {"type": "plain_text", "text": "Meal Order Open"},
        },
        {
            "type": "section",
            "text": {
                "type": "mrkdwn",
                "text": (
                    f"*<{form_url}|Place your order>*\n\n"
                    f"*Deadline:* Thursday at 11:59pm\n"
                    f"*Menu:* {meal_count} meals available"
                ),
            },
        },
    ]

    post_channel_message(text, blocks)
    return {"status": "notified", "event": "menu_published", "week": week}


def handle_orders_aggregated(event):
    week = event.get("week", current_week())
    summary = get_summary(week)
    if not summary:
        return {"status": "no_summary", "week": week}

    total_employees = int(summary.get("total_employees", 0))
    total_meals = int(summary.get("total_meals", 0))
    grand_total = float(summary.get("grand_total", 0))
    employee_total = float(summary.get("employee_total", grand_total))

    meal_lines = []
    for m in summary.get("meals", []):
        meal_lines.append(f"{m['meal']}: *{int(m['quantity'])}*")
    meal_list = "\n".join(meal_lines)

    has_subsidy = employee_total < grand_total
    totals_text = (
        f"*${grand_total:.2f}* order total (bulk rate)\n"
        f"*${employee_total:.2f}* payroll deductions"
        + (f"\n*${grand_total - employee_total:.2f}* company subsidy" if has_subsidy else "")
    )

    text = f"Meal orders closed for {week}. {total_employees} employees, {total_meals} meals, ${grand_total:.2f} total."
    blocks = [
        {
            "type": "header",
            "text": {"type": "plain_text", "text": f"Meal Orders Closed — {week}"},
        },
        {
            "type": "section",
            "text": {
                "type": "mrkdwn",
                "text": (
                    f"*{total_employees}* employees ordered\n"
                    f"*{total_meals}* total meals\n"
                    f"{totals_text}"
                ),
            },
        },
        {"type": "divider"},
        {
            "type": "section",
            "text": {
                "type": "mrkdwn",
                "text": f"*Order for Redefine Meals:*\n{meal_list}",
            },
        },
    ]

    post_channel_message(text, blocks)
    return {"status": "notified", "event": "orders_aggregated", "week": week}


def handle_order_confirmed(event):
    email = event.get("employee_email", "").lower()
    name = event.get("employee_name", "")
    items = event.get("items", [])
    total = float(event.get("total", 0))
    week = event.get("week", current_week())

    roster = get_roster()
    employee = next((e for e in roster if e["email"].lower() == email), None)
    if not employee or not employee.get("slack_user_id"):
        return {"status": "no_slack_id", "email": email}

    item_lines = []
    for item in items:
        qty = int(item.get("quantity", 0))
        price = float(item.get("price", 0))
        item_lines.append(f"{item['name']} x{qty} — ${price * qty:.2f}")
    item_list = "\n".join(item_lines)

    send_dm(
        employee["slack_user_id"],
        f"Order confirmed for {week}: ${total:.2f} total.",
        blocks=[
            {
                "type": "header",
                "text": {"type": "plain_text", "text": f"Order Confirmed — {week}"},
            },
            {
                "type": "section",
                "text": {
                    "type": "mrkdwn",
                    "text": (
                        f"Hey {name.split()[0]}! Your meal order has been submitted.\n\n"
                        f"{item_list}\n\n"
                        f"*Total: ${total:.2f}*"
                    ),
                },
            },
        ],
    )

    return {"status": "confirmed", "week": week, "employee": name}


def handle_reminder(event):
    week = event.get("week", current_week())
    form_url = os.environ.get("FORM_URL", "")

    roster = get_roster()
    if not roster:
        return {"status": "no_roster"}

    orders = get_orders(week)
    ordered_emails = {o["employee_email"].lower() for o in orders}

    missing = [emp for emp in roster if emp["email"].lower() not in ordered_emails]

    dm_count = 0
    for emp in missing:
        slack_id = emp.get("slack_user_id")
        if not slack_id:
            continue
        send_dm(
            slack_id,
            f"Meal orders close today at 11:59pm. Place your order: {form_url}",
            blocks=[
                {
                    "type": "section",
                    "text": {
                        "type": "mrkdwn",
                        "text": (
                            f"Hey {emp['name'].split()[0]}! Meal orders close today at *11:59pm*.\n\n"
                            f"*<{form_url}|Place your order>*"
                        ),
                    },
                }
            ],
        )
        dm_count += 1

    return {
        "status": "reminders_sent",
        "week": week,
        "dm_count": dm_count,
        "missing_count": len(missing),
    }