import email
import logging
import os
import re
from datetime import datetime
from email import policy

import boto3

logger = logging.getLogger()
logger.setLevel(logging.INFO)

s3 = boto3.client("s3")
dynamodb = boto3.resource("dynamodb")

VENDOR_REPLIES_TABLE = os.environ.get("VENDOR_REPLIES_TABLE", "VendorReplies")


def parse_raw_email(raw_bytes):
    msg = email.message_from_bytes(raw_bytes, policy=policy.default)

    subject = msg.get("Subject", "")
    sender = msg.get("From", "")
    to = msg.get("To", "")
    date = msg.get("Date", "")

    body = ""
    if msg.is_multipart():
        for part in msg.walk():
            content_type = part.get_content_type()
            if content_type == "text/plain":
                body = part.get_content()
                break
            elif content_type == "text/html" and not body:
                body = part.get_content()
    else:
        body = msg.get_content()

    body = strip_quoted_reply(body)

    return {
        "subject": subject,
        "sender": sender,
        "to": to,
        "date": date,
        "body": body,
    }


def strip_quoted_reply(text):
    if not text:
        return ""
    lines = text.split("\n")
    result = []
    for line in lines:
        if re.match(r"^On .+ wrote:$", line.strip()):
            break
        if line.strip().startswith("---Original Message---"):
            break
        if line.strip().startswith("> "):
            continue
        result.append(line)
    return "\n".join(result).strip()


def extract_ids_from_subject(subject):
    wo_match = re.search(r"\[WO-(\d{8})", subject)
    dsp_match = re.search(r"(DSP-\d{5})", subject)

    wo_number = wo_match.group(1) if wo_match else None
    dispatch_number = dsp_match.group(1) if dsp_match else None

    return wo_number, dispatch_number


def extract_sender_email(sender):
    match = re.search(r"<(.+?)>", sender)
    if match:
        return match.group(1)
    return sender.strip()


def handler(event, context):
    for record in event.get("Records", []):
        bucket = record["s3"]["bucket"]["name"]
        key = record["s3"]["object"]["key"]

        logger.info(f"Processing vendor reply: s3://{bucket}/{key}")

        response = s3.get_object(Bucket=bucket, Key=key)
        raw_email = response["Body"].read()

        email_data = parse_raw_email(raw_email)
        logger.info(f"Subject: {email_data['subject']}")
        logger.info(f"From: {email_data['sender']}")

        wo_number, dispatch_number = extract_ids_from_subject(email_data["subject"])

        if not wo_number:
            logger.warning(f"No WO number found in subject, skipping: {key}")
            continue

        sender_email = extract_sender_email(email_data["sender"])
        now = datetime.utcnow().isoformat()
        reply_id = f"{wo_number}#{dispatch_number or 'none'}#{now}"

        table = dynamodb.Table(VENDOR_REPLIES_TABLE)
        table.put_item(
            Item={
                "internal_wo_number": wo_number,
                "reply_id": reply_id,
                "dispatch_number": dispatch_number or "",
                "sender_email": sender_email,
                "reply_text": email_data["body"],
                "subject": email_data["subject"],
                "received_at": now,
                "source_email_s3_key": f"s3://{bucket}/{key}",
                "synced": False,
            }
        )

        logger.info(
            f"Saved vendor reply: WO={wo_number} DSP={dispatch_number} from={sender_email}"
        )

    return {"statusCode": 200, "body": "OK"}