# app/api/v1/vendor/email_templates.py
"""
Vendor email template override endpoints.

Allows vendors to customize platform email templates with their own content.
Platform-only templates (billing, subscription) cannot be overridden.

Vendor Context: Uses token_vendor_id from JWT token (authenticated vendor API pattern).
"""

import logging
from typing import Any

from fastapi import APIRouter, Depends, HTTPException
from jinja2 import Template
from pydantic import BaseModel, EmailStr, Field
from sqlalchemy.orm import Session

from app.api.deps import get_current_vendor_api
from app.core.database import get_db
from app.services.email_service import EmailService
from app.services.vendor_service import vendor_service
from models.database.email import EmailTemplate
from models.database.user import User
from models.database.vendor_email_template import VendorEmailTemplate

router = APIRouter(prefix="/email-templates")
logger = logging.getLogger(__name__)

# Supported languages
SUPPORTED_LANGUAGES = ["en", "fr", "de", "lb"]


class VendorTemplateUpdate(BaseModel):
    """Schema for creating/updating a vendor template override."""

    subject: str = Field(..., min_length=1, max_length=500)
    body_html: str = Field(..., min_length=1)
    body_text: str | None = None
    name: str | None = Field(None, max_length=255)


class TemplatePreviewRequest(BaseModel):
    """Schema for previewing a template."""

    language: str = "en"
    variables: dict[str, Any] = {}


class TemplateTestRequest(BaseModel):
    """Schema for sending a test email."""

    to_email: EmailStr
    language: str = "en"
    variables: dict[str, Any] = {}


@router.get("")
def list_overridable_templates(
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    List all email templates that the vendor can customize.

    Returns platform templates with vendor override status.
    Platform-only templates (billing, subscription) are excluded.
    """
    vendor_id = current_user.token_vendor_id

    # Get all overridable platform templates
    platform_templates = EmailTemplate.get_overridable_templates(db)

    # Get all vendor overrides
    vendor_overrides = VendorEmailTemplate.get_all_overrides_for_vendor(db, vendor_id)

    # Build override lookup
    override_lookup = {}
    for override in vendor_overrides:
        key = (override.template_code, override.language)
        override_lookup[key] = override

    # Build response
    templates_response = []
    for template in platform_templates:
        # Check which languages have overrides
        override_languages = []
        for lang in SUPPORTED_LANGUAGES:
            if (template.code, lang) in override_lookup:
                override_languages.append(lang)

        templates_response.append({
            "code": template.code,
            "name": template.name,
            "category": template.category,
            "description": template.description,
            "available_languages": _get_available_languages(db, template.code),
            "override_languages": override_languages,
            "has_override": len(override_languages) > 0,
            "variables": template.required_variables.split(",") if template.required_variables else [],
        })

    return {
        "templates": templates_response,
        "supported_languages": SUPPORTED_LANGUAGES,
    }


@router.get("/{code}")
def get_template(
    code: str,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Get a specific template with all language versions.

    Returns platform template details and vendor overrides for each language.
    """
    vendor_id = current_user.token_vendor_id

    # Get platform template
    platform_template = db.query(EmailTemplate).filter(
        EmailTemplate.code == code
    ).first()

    if not platform_template:
        raise HTTPException(status_code=404, detail="Template not found")

    if platform_template.is_platform_only:
        raise HTTPException(
            status_code=403,
            detail="This is a platform-only template and cannot be customized"
        )

    # Get all language versions of platform template
    platform_versions = db.query(EmailTemplate).filter(
        EmailTemplate.code == code
    ).all()

    # Get vendor overrides for all languages
    vendor_overrides = (
        db.query(VendorEmailTemplate)
        .filter(
            VendorEmailTemplate.vendor_id == vendor_id,
            VendorEmailTemplate.template_code == code,
        )
        .all()
    )

    override_lookup = {v.language: v for v in vendor_overrides}
    platform_lookup = {t.language: t for t in platform_versions}

    # Build language versions
    languages = {}
    for lang in SUPPORTED_LANGUAGES:
        platform_ver = platform_lookup.get(lang)
        override_ver = override_lookup.get(lang)

        languages[lang] = {
            "has_platform_template": platform_ver is not None,
            "has_vendor_override": override_ver is not None,
            "platform": {
                "subject": platform_ver.subject if platform_ver else None,
                "body_html": platform_ver.body_html if platform_ver else None,
                "body_text": platform_ver.body_text if platform_ver else None,
            } if platform_ver else None,
            "vendor_override": {
                "subject": override_ver.subject if override_ver else None,
                "body_html": override_ver.body_html if override_ver else None,
                "body_text": override_ver.body_text if override_ver else None,
                "name": override_ver.name if override_ver else None,
                "updated_at": override_ver.updated_at.isoformat() if override_ver else None,
            } if override_ver else None,
        }

    return {
        "code": code,
        "name": platform_template.name,
        "category": platform_template.category,
        "description": platform_template.description,
        "variables": platform_template.required_variables.split(",") if platform_template.required_variables else [],
        "languages": languages,
    }


@router.get("/{code}/{language}")
def get_template_language(
    code: str,
    language: str,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Get a specific template for a specific language.

    Returns vendor override if exists, otherwise platform template.
    """
    if language not in SUPPORTED_LANGUAGES:
        raise HTTPException(status_code=400, detail=f"Unsupported language: {language}")

    vendor_id = current_user.token_vendor_id

    # Check if template is overridable
    platform_template = db.query(EmailTemplate).filter(
        EmailTemplate.code == code
    ).first()

    if not platform_template:
        raise HTTPException(status_code=404, detail="Template not found")

    if platform_template.is_platform_only:
        raise HTTPException(
            status_code=403,
            detail="This is a platform-only template and cannot be customized"
        )

    # Check for vendor override
    vendor_override = VendorEmailTemplate.get_override(db, vendor_id, code, language)

    # Get platform version for this language
    platform_version = EmailTemplate.get_by_code_and_language(db, code, language)

    if vendor_override:
        return {
            "code": code,
            "language": language,
            "source": "vendor_override",
            "subject": vendor_override.subject,
            "body_html": vendor_override.body_html,
            "body_text": vendor_override.body_text,
            "name": vendor_override.name,
            "variables": platform_template.required_variables.split(",") if platform_template.required_variables else [],
            "platform_template": {
                "subject": platform_version.subject if platform_version else None,
                "body_html": platform_version.body_html if platform_version else None,
            } if platform_version else None,
        }
    elif platform_version:
        return {
            "code": code,
            "language": language,
            "source": "platform",
            "subject": platform_version.subject,
            "body_html": platform_version.body_html,
            "body_text": platform_version.body_text,
            "name": platform_version.name,
            "variables": platform_template.required_variables.split(",") if platform_template.required_variables else [],
            "platform_template": None,
        }
    else:
        raise HTTPException(
            status_code=404,
            detail=f"No template found for language: {language}"
        )


@router.put("/{code}/{language}")
def update_template_override(
    code: str,
    language: str,
    template_data: VendorTemplateUpdate,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Create or update a vendor template override.

    Creates a vendor-specific version of the email template.
    The platform template remains unchanged.
    """
    if language not in SUPPORTED_LANGUAGES:
        raise HTTPException(status_code=400, detail=f"Unsupported language: {language}")

    vendor_id = current_user.token_vendor_id

    # Check if template exists and is overridable
    platform_template = db.query(EmailTemplate).filter(
        EmailTemplate.code == code
    ).first()

    if not platform_template:
        raise HTTPException(status_code=404, detail="Template not found")

    if platform_template.is_platform_only:
        raise HTTPException(
            status_code=403,
            detail="This is a platform-only template and cannot be customized"
        )

    # Validate template content (try to render with dummy variables)
    try:
        Template(template_data.subject).render({})
        Template(template_data.body_html).render({})
        if template_data.body_text:
            Template(template_data.body_text).render({})
    except Exception as e:
        raise HTTPException(
            status_code=400,
            detail=f"Invalid template syntax: {str(e)}"
        )

    # Create or update override
    override = VendorEmailTemplate.create_or_update(
        db=db,
        vendor_id=vendor_id,
        template_code=code,
        language=language,
        subject=template_data.subject,
        body_html=template_data.body_html,
        body_text=template_data.body_text,
        name=template_data.name,
    )

    db.commit()

    logger.info(
        f"Vendor {vendor_id} updated email template override: {code}/{language}"
    )

    return {
        "message": "Template override saved",
        "code": code,
        "language": language,
        "is_new": override.created_at == override.updated_at,
    }


@router.delete("/{code}/{language}")
def delete_template_override(
    code: str,
    language: str,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Delete a vendor template override.

    Reverts to using the platform default template for this language.
    """
    if language not in SUPPORTED_LANGUAGES:
        raise HTTPException(status_code=400, detail=f"Unsupported language: {language}")

    vendor_id = current_user.token_vendor_id

    deleted = VendorEmailTemplate.delete_override(db, vendor_id, code, language)

    if not deleted:
        raise HTTPException(
            status_code=404,
            detail="No override found for this template and language"
        )

    db.commit()

    logger.info(
        f"Vendor {vendor_id} deleted email template override: {code}/{language}"
    )

    return {
        "message": "Template override deleted - reverted to platform default",
        "code": code,
        "language": language,
    }


@router.post("/{code}/preview")
def preview_template(
    code: str,
    preview_data: TemplatePreviewRequest,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Preview a template with sample variables.

    Uses vendor override if exists, otherwise platform template.
    """
    vendor_id = current_user.token_vendor_id
    vendor = vendor_service.get_vendor_by_id(db, vendor_id)

    # Check if template exists
    platform_template = db.query(EmailTemplate).filter(
        EmailTemplate.code == code
    ).first()

    if not platform_template:
        raise HTTPException(status_code=404, detail="Template not found")

    # Get template content (vendor override or platform)
    vendor_override = VendorEmailTemplate.get_override(
        db, vendor_id, code, preview_data.language
    )
    platform_version = EmailTemplate.get_by_code_and_language(
        db, code, preview_data.language
    )

    if vendor_override:
        subject = vendor_override.subject
        body_html = vendor_override.body_html
        body_text = vendor_override.body_text
        source = "vendor_override"
    elif platform_version:
        subject = platform_version.subject
        body_html = platform_version.body_html
        body_text = platform_version.body_text
        source = "platform"
    else:
        raise HTTPException(
            status_code=404,
            detail=f"No template found for language: {preview_data.language}"
        )

    # Add branding variables
    variables = {
        **preview_data.variables,
        "platform_name": "Wizamart",
        "vendor_name": vendor.name,
        "support_email": vendor.contact_email or "support@wizamart.com",
    }

    # Render templates
    try:
        rendered_subject = Template(subject).render(variables)
        rendered_html = Template(body_html).render(variables)
        rendered_text = Template(body_text).render(variables) if body_text else None
    except Exception as e:
        raise HTTPException(
            status_code=400,
            detail=f"Template rendering error: {str(e)}"
        )

    return {
        "source": source,
        "language": preview_data.language,
        "subject": rendered_subject,
        "body_html": rendered_html,
        "body_text": rendered_text,
    }


@router.post("/{code}/test")
def send_test_email(
    code: str,
    test_data: TemplateTestRequest,
    current_user: User = Depends(get_current_vendor_api),
    db: Session = Depends(get_db),
):
    """
    Send a test email using the template.

    Uses vendor override if exists, otherwise platform template.
    """
    vendor_id = current_user.token_vendor_id
    vendor = vendor_service.get_vendor_by_id(db, vendor_id)

    # Check if template exists
    platform_template = db.query(EmailTemplate).filter(
        EmailTemplate.code == code
    ).first()

    if not platform_template:
        raise HTTPException(status_code=404, detail="Template not found")

    # Build test variables
    variables = {
        **_get_sample_variables(code),
        **test_data.variables,
        "platform_name": "Wizamart",
        "vendor_name": vendor.name,
        "support_email": vendor.contact_email or "support@wizamart.com",
    }

    try:
        # Send using email service (will use vendor override if exists)
        email_svc = EmailService(db)
        email_log = email_svc.send_template(
            template_code=code,
            to_email=test_data.to_email,
            variables=variables,
            vendor_id=vendor_id,
            language=test_data.language,
        )

        if email_log.status == "sent":
            return {
                "success": True,
                "message": f"Test email sent to {test_data.to_email}",
            }
        else:
            return {
                "success": False,
                "message": email_log.error_message or "Failed to send email",
            }
    except Exception as e:
        logger.exception(f"Failed to send test email: {e}")
        return {
            "success": False,
            "message": str(e),
        }


def _get_available_languages(db: Session, code: str) -> list[str]:
    """Get list of languages that have platform templates."""
    templates = db.query(EmailTemplate.language).filter(
        EmailTemplate.code == code
    ).all()
    return [t.language for t in templates]


def _get_sample_variables(template_code: str) -> dict[str, Any]:
    """Get sample variables for testing templates."""
    samples = {
        "signup_welcome": {
            "first_name": "John",
            "company_name": "Acme Corp",
            "email": "john@example.com",
            "vendor_code": "acme",
            "login_url": "https://example.com/login",
            "trial_days": "14",
            "tier_name": "Business",
        },
        "order_confirmation": {
            "customer_name": "Jane Doe",
            "order_number": "ORD-12345",
            "order_total": "99.99",
            "order_items_count": "3",
            "order_date": "2024-01-15",
            "shipping_address": "123 Main St, Luxembourg City, L-1234",
        },
        "password_reset": {
            "customer_name": "John Doe",
            "reset_link": "https://example.com/reset?token=abc123",
            "expiry_hours": "1",
        },
        "team_invite": {
            "invitee_name": "Jane",
            "inviter_name": "John",
            "vendor_name": "Acme Corp",
            "role": "Admin",
            "accept_url": "https://example.com/accept",
            "expires_in_days": "7",
        },
    }
    return samples.get(template_code, {"platform_name": "Wizamart"})