"""Discord-facing reminder command handler and parser validation."""

from datetime import datetime, timezone

from core import users
from modules.reminders import service


VALID_ACTIONS = {"create", "list", "cancel", "set_timezone"}


def validateReminder(data):
    if not isinstance(data, dict):
        return ["Response must be a JSON object"]
    if data.get("needs_clarification"):
        return []

    errors = []
    action = data.get("action")
    if action not in VALID_ACTIONS:
        errors.append("action must be create, list, cancel, or set_timezone")
        return errors

    if action == "create":
        if not isinstance(data.get("message"), str) or not data["message"].strip():
            errors.append("create requires a reminder message")
        try:
            runAt = datetime.fromisoformat(
                str(data.get("run_at", "")).replace("Z", "+00:00")
            )
            if runAt.tzinfo is None:
                errors.append("run_at must include a timezone offset")
            elif runAt.astimezone(timezone.utc) <= datetime.now(timezone.utc):
                errors.append("run_at must be in the future")
        except ValueError:
            errors.append("create requires an ISO-8601 run_at")
        try:
            service.normalizeRecurrence(data.get("recurrence"))
        except ValueError as error:
            errors.append(str(error))
    elif action == "cancel" and not data.get("reminder_id"):
        errors.append("cancel requires reminder_id from the reminder list")
    elif action == "set_timezone" and not users.isValidTimezone(data.get("timezone")):
        errors.append("set_timezone requires a valid IANA timezone")
    return errors


async def handleReminder(context, parsed):
    action = parsed["action"]
    if action == "create":
        result, status = await context.api.request(
            "post",
            "/api/reminders",
            {
                "message": parsed["message"],
                "run_at": parsed["run_at"],
                "recurrence": parsed.get("recurrence"),
            },
        )
        if status == 201:
            recurrence = " (recurring)" if result.get("recurrence") else ""
            await context.reply(
                f"Reminder set for **{result['next_run_at']}**{recurrence}: "
                f"{result['message']}"
            )
        else:
            await context.reply(_errorMessage(result, "I couldn't create that reminder."))
        return

    if action == "list":
        result, status = await context.api.request("get", "/api/reminders")
        if status != 200:
            await context.reply(_errorMessage(result, "I couldn't list reminders."))
            return
        reminders = result.get("reminders", [])
        if not reminders:
            await context.reply("You have no active reminders.")
            return
        lines = [
            f"- `{item['id']}` — {item['next_run_at']}: {item['message']}"
            for item in reminders
        ]
        await context.reply("**Active reminders:**\n" + "\n".join(lines))
        return

    if action == "cancel":
        result, status = await context.api.request(
            "delete", f"/api/reminders/{parsed['reminder_id']}"
        )
        if status == 200:
            await context.reply(f"Cancelled reminder: {result['message']}")
        else:
            await context.reply(_errorMessage(result, "I couldn't cancel that reminder."))
        return

    result, status = await context.api.request(
        "put", "/api/user/me/timezone", {"timezone": parsed["timezone"]}
    )
    if status == 200:
        context.api.timezone = result["timezone"]
        context.timezone = result["timezone"]
        await context.reply(f"Your timezone is now **{result['timezone']}**.")
    else:
        await context.reply(_errorMessage(result, "I couldn't update your timezone."))


def _errorMessage(result, fallback):
    detail = result.get("error") if isinstance(result, dict) else None
    return f"{fallback} {detail}" if detail else fallback