"""
Email sender module for ScrAIbe.

Sends transcription outputs (TXT, JSON, etc.) via SMTP.
All credentials are configured via environment variables.
Supports both plain text and HTML email bodies.
Template placeholders are primarily filled via environment variables.
"""

import base64
import os
import re
import smtplib
import logging
from email import encoders
from email.mime.base import MIMEBase
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from typing import List, Optional, Dict, Any

from docx import Document
from docx.shared import Inches, Pt
from docx.oxml.ns import qn
from docx.oxml import OxmlElement

logger = logging.getLogger("scraibe.email_sender")


class EmailError(Exception):
    pass


def get_email_config():
    """
    Read email configuration from environment variables.
    Raises EmailError if required fields are missing.
    """
    smtp_host = os.getenv("EMAIL_SMTP_HOST")
    smtp_port = os.getenv("EMAIL_SMTP_PORT")
    smtp_user = os.getenv("EMAIL_SMTP_USER")
    smtp_password = os.getenv("EMAIL_SMTP_PASSWORD")
    from_address = os.getenv("EMAIL_FROM_ADDRESS")
    use_tls_str = os.getenv("EMAIL_SMTP_USE_TLS", "true").strip().lower()
    use_tls = use_tls_str not in ("false", "0", "no")

    if not all([smtp_host, smtp_port, smtp_user, smtp_password, from_address]):
        raise EmailError(
            "Email configuration incomplete. "
            "Ensure EMAIL_SMTP_HOST, EMAIL_SMTP_PORT, EMAIL_SMTP_USER, "
            "EMAIL_SMTP_PASSWORD, and EMAIL_FROM_ADDRESS are set."
        )

    return {
        "smtp_host": smtp_host,
        "smtp_port": int(smtp_port),
        "smtp_user": smtp_user,
        "smtp_password": smtp_password,
        "from_address": from_address,
        "use_tls": use_tls,
    }


def _load_css(path: str) -> str:
    """
    Load CSS file content if it exists.
    """
    if not path or not os.path.exists(path):
        return ""
    with open(path, "r", encoding="utf-8") as f:
        return f.read()


def _email_logo_html() -> str:
    """
    Return a subtle watermark-style logo for emails.

    - Priority:
      1) EMAIL_LOGO_URL (direct URL)
      2) EMAIL_LOGO_PATH (local file as base64)
    - Style: small, faint, bottom-right, non-intrusive.
    """
    logo_url = os.getenv("EMAIL_LOGO_URL")
    src = logo_url

    if not logo_url:
        logo_path = os.getenv("EMAIL_LOGO_PATH", "/app/src/misc/logo1.png")
        if os.path.exists(logo_path):
            try:
                with open(logo_path, "rb") as f:
                    b64 = base64.b64encode(f.read()).decode("utf-8")
                src = f"data:image/png;base64,{b64}"
            except Exception:
                src = None

    if not src:
        return ""

    # Watermark: bottom-right, low opacity, compact
    return (
        f'<div style="text-align: right; margin-top: 24px; opacity: 0.15;">'
        f'<img src="{src}" alt="Logo" style="max-width: 90px; height: auto; display: inline-block;" />'
        f'</div>'
    )


def _accent_color() -> str:
    """
    Accent color for UI and emails.
    Default: #7C6DA0
    """
    return os.getenv("EMAIL_ACCENT_COLOR", "#7C6DA0")


def build_template_context(**runtime_kwargs: Any) -> Dict[str, Any]:
    """
    Build a context dict for templates from:
      - environment variables (base, customizable)
      - runtime-provided values (override env if present)

    Environment variables:
      - EMAIL_CONTACT_ADDRESS: value for {contact_email}
      - EMAIL_CSS_PATH: path to mail_style.css (optional; we inline it)
      - EMAIL_LOGO_URL: URL for email logo (preferred)
      - EMAIL_LOGO_PATH: fallback local path for email logo
      - EMAIL_ACCENT_COLOR: accent color (default #7C6DA0)
    """
    # Load and inline mail_style.css for consistent email styling
    css_path = os.getenv("EMAIL_CSS_PATH", "/app/src/misc/mail_style.css")
    css_text = _load_css(css_path)

    # Build logo HTML (URL or local fallback)
    logo_html = _email_logo_html()

    # Accent color
    accent = _accent_color()

    ctx: Dict[str, Any] = {
        "contact_email": os.getenv("EMAIL_CONTACT_ADDRESS", "support@example.com"),
        "email_css": css_text,
        "email_logo": logo_html,
        "accent_color": accent,
    }

    # Runtime values override env if provided
    if runtime_kwargs:
        ctx.update(runtime_kwargs)

    return ctx


def load_template(template_name: str, **runtime_kwargs: Any) -> str:
    """
    Load an HTML email template from misc/ and render placeholders.

    Expects files like:
        /app/src/misc/upload_notification_template.html
        /app/src/misc/success_template.html
        /app/src/misc/error_notification_template.html
    """
    base = os.getenv("SCRAIBE_TEMPLATES_DIR", "/app/src/misc")
    path = os.path.join(base, template_name)

    if not os.path.exists(path):
        raise EmailError(f"Email template not found: {path}")

    with open(path, "r", encoding="utf-8") as f:
        template = f.read()

    # Build context from env + runtime
    ctx = build_template_context(**runtime_kwargs)

    # Replace {placeholder} style variables safely
    try:
        return template.format(**ctx)
    except KeyError as e:
        raise EmailError(f"Missing template variable: {e}")


def send_email(
    to: str,
    subject: str,
    body: str,
    html: Optional[str],
    attachments: List[str],
    cc: Optional[str] = None,
) -> bool:
    """
    Send an email with optional HTML body and file attachments.

    Args:
        to: Comma-separated list of recipient email addresses.
        subject: Email subject.
        body: Email body (plain text).
        html: Email body (HTML), or None.
        attachments: List of file paths to attach.
        cc: Comma-separated list of CC email addresses (optional).

    Returns:
        True if sent successfully.

    Raises:
        EmailError if sending fails.
    """
    try:
        cfg = get_email_config()
    except EmailError as e:
        logger.error("Email configuration error: %s", e)
        raise

    # Parse recipients
    to_list = [addr.strip() for addr in to.split(",") if addr.strip()]
    cc_list = [addr.strip() for addr in cc.split(",") if addr.strip()] if cc else []

    if not to_list:
        raise EmailError("No valid 'To' email addresses provided.")

    # Build message
    msg = MIMEMultipart("alternative")
    msg["From"] = cfg["from_address"]
    msg["To"] = ", ".join(to_list)
    if cc_list:
        msg["Cc"] = ", ".join(cc_list)
    msg["Subject"] = subject

    # Attach plain text
    msg.attach(MIMEText(body, "plain"))

    # Attach HTML if provided
    if html:
        msg.attach(MIMEText(html, "html"))

    # Attach files in a separate multipart/mixed part
    if attachments:
        mixed = MIMEMultipart("mixed")
        mixed.attach(msg)
        msg = mixed

        for file_path in attachments:
            if not os.path.isfile(file_path):
                logger.warning("Attachment file not found, skipping: %s", file_path)
                continue

            try:
                with open(file_path, "rb") as f:
                    part = MIMEBase("application", "octet-stream")
                    part.set_payload(f.read())
                    encoders.encode_base64(part)
                    part.add_header(
                        "Content-Disposition",
                        "attachment",
                        filename=os.path.basename(file_path),
                    )
                    msg.attach(part)
            except Exception as e:
                logger.warning("Failed to attach file %s: %s", file_path, e)

    # Connect and send
    try:
        if cfg["use_tls"]:
            server = smtplib.SMTP(cfg["smtp_host"], cfg["smtp_port"], timeout=30)
            server.ehlo()
            server.starttls()
            server.ehlo()
        else:
            server = smtplib.SMTP(cfg["smtp_host"], cfg["smtp_port"], timeout=30)
            server.ehlo()

        server.login(cfg["smtp_user"], cfg["smtp_password"])
        server.sendmail(
            cfg["from_address"],
            to_list + cc_list,
            msg.as_string(),
        )
        server.quit()
        logger.info(
            "Email sent to %s (CC: %s)",
            to_list,
            cc_list or "None",
        )
        return True

    except Exception as e:
        logger.error("Failed to send email: %s", e)
        raise EmailError(f"Failed to send email: {e}")


def create_transcript_docx(text: str, filename: str):
    """
    Create a .docx transcript with:
      - 1.5" left margin, 1" right margin
      - 12pt Courier
      - Continuous line numbering on the left
      - Speaker names capitalized and indented; spoken text further indented
      - No section headings; use bold/underline only.
    """
    doc = Document()

    # Set margins via section properties
    section = doc.sections[0]
    section.left_margin = Inches(1.5)
    section.right_margin = Inches(1.0)
    section.top_margin = Inches(1.0)
    section.bottom_margin = Inches(1.0)

    # Enable continuous line numbering on the left
    sectPr = section._sectPr
    lnNumType = sectPr.find(qn("w:lnNumType"))
    if lnNumType is None:
        lnNumType = OxmlElement("w:lnNumType")
        sectPr.append(lnNumType)
    lnNumType.set(qn("w:start"), "continuous")
    lnNumType.set(qn("w:countBy"), "1")

    # Default font
    style = doc.styles["Normal"]
    font = style.font
    font.name = "Courier"
    font.size = Pt(12)

    # Parse lines
    lines = text.strip().split("\n")
    for line in lines:
        line = line.strip()
        if not line:
            continue

        # Try to parse: [00:00] SPEAKER: text
        m = re.match(r"\[(\d+:\d+(?::\d+)?)\]\s*(.+?):\s*(.*)", line)
        if m:
            ts, speaker, content = m.groups()
            # Speaker line: bold, underlined, indented
            p_spk = doc.add_paragraph()
            p_spk.paragraph_format.left_indent = Inches(0.25)
            run_spk = p_spk.add_run(f"[{ts}] {speaker.upper()}")
            run_spk.bold = True
            run_spk.underline = True
            run_spk.font.name = "Courier"
            run_spk.font.size = Pt(12)

            # Spoken text line: further indented
            p_txt = doc.add_paragraph()
            p_txt.paragraph_format.left_indent = Inches(0.5)
            run_txt = p_txt.add_run(content.strip())
            run_txt.font.name = "Courier"
            run_txt.font.size = Pt(12)
        else:
            # Fallback for non-standard lines
            p = doc.add_paragraph()
            run = p.add_run(line)
            run.font.name = "Courier"
            run.font.size = Pt(12)

    doc.save(filename)


def create_summary_docx(text: str, filename: str):
    """
    Create a .docx summary with consistent font.
    No section headings; use bold/underline only.
    """
    doc = Document()
    style = doc.styles["Normal"]
    font = style.font
    font.name = "Courier"
    font.size = Pt(12)

    for line in text.splitlines():
        p = doc.add_paragraph(line)
        p.paragraph_format.space_after = Pt(4)

    doc.save(filename)