"""
Copyright 2024-2026 ChatterMate

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""

import enum
import uuid

from sqlalchemy import Column, DateTime, ForeignKey, Index, Integer, String, Text
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func

from app.database import Base

DEFAULT_FAQ_CATEGORY = "General"
# Column widths, kept here so the API schemas bound input to exactly what the
# columns accept instead of restating the numbers (see models.schemas.faq).
FAQ_SLUG_MAX_LENGTH = 80
FAQ_META_TITLE_MAX_LENGTH = 120
FAQ_META_DESCRIPTION_MAX_LENGTH = 300
FAQ_URL_PATH_MAX_LENGTH = 400
FAQ_SOURCE_URL_MAX_LENGTH = 2048


class FAQStatus(str, enum.Enum):
    DRAFT = "draft"
    PUBLISHED = "published"


class FAQ(Base):
    """A single question/answer pair shown on the org's public help center.

    FAQs are a standalone projection of the knowledge base: generation only
    reads knowledge content, and editing/deleting FAQs never touches the
    knowledge tables. Drafts stay private until explicitly published.
    """
    __tablename__ = "faqs"

    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
    # No single-column index: both composite indexes below lead with org id.
    organization_id = Column(
        UUID(as_uuid=True),
        ForeignKey("organizations.id", ondelete="CASCADE"),
        nullable=False,
    )
    question = Column(Text, nullable=False)
    # Answer is authored/stored as Markdown; rendered to sanitized HTML on the
    # public article page (app.services.help_center_content).
    answer = Column(Text, nullable=False)
    # URL slug for the public article page (/a/{slug}). Assigned from the
    # question at creation and kept stable so published article URLs don't churn
    # on edits — but editable by hand for SEO (app.api.help_center.faqs).
    # Unique per org (see ix_faqs_org_slug); NULL until assigned.
    slug = Column(String(FAQ_SLUG_MAX_LENGTH), nullable=True)
    # The original URL path of an article migrated in from another help center.
    # When set, the article is SERVED at this exact path and /a/{slug} 301s to
    # it, so the org keeps the URLs it already ranks for instead of losing that
    # SEO to a migration. Root-relative, no trailing slash, and percent-DECODED
    # because that is the form the ASGI scope hands us to match against (every
    # emitted URL re-encodes it — see help_center_seo.article_url).
    # Unique per org (see ix_faqs_org_url_path); NULL means "served at /a/{slug}",
    # which is every article that wasn't migrated.
    url_path = Column(String(FAQ_URL_PATH_MAX_LENGTH), nullable=True)
    # Where an imported article was fetched from, post-redirect. Provenance only
    # — never routed on — and kept even when url_path had to be dropped, so the
    # original URL is still recoverable.
    source_url = Column(String(FAQ_SOURCE_URL_MAX_LENGTH), nullable=True)
    # Per-article SEO overrides for the public page's <title> and meta
    # description. NULL means "derive from the content": the question and an
    # excerpt of the answer (see app.api.help_center_public). Lengths mirror
    # help_center_settings.title/description.
    meta_title = Column(String(FAQ_META_TITLE_MAX_LENGTH), nullable=True)
    meta_description = Column(String(FAQ_META_DESCRIPTION_MAX_LENGTH), nullable=True)
    # Free-form category assigned by the LLM grouping step (or the user).
    category = Column(String(100), nullable=False, default=DEFAULT_FAQ_CATEGORY)
    # Plain string (values from FAQStatus), like knowledge_queue.status — new
    # states never need an ALTER TYPE migration.
    status = Column(String, nullable=False, default=FAQStatus.DRAFT)
    # Provenance: the knowledge source it was generated from (if any) plus a
    # human-readable label ("example.com/docs", "Imported from support.x.com",
    # "Added manually") that survives source deletion.
    knowledge_id = Column(Integer, ForeignKey("knowledge.id", ondelete="SET NULL"), nullable=True, index=True)
    source_label = Column(String(255), nullable=True)
    generation_job_id = Column(
        Integer, ForeignKey("faq_generation_jobs.id", ondelete="SET NULL"), nullable=True, index=True
    )
    created_by = Column(UUID(as_uuid=True), ForeignKey("users.id", ondelete="SET NULL"), nullable=True)
    sort_order = Column(Integer, nullable=False, default=0)
    # "Was this helpful?" tallies (de-duplicated per IP/day at the API).
    helpful_yes = Column(Integer, nullable=False, default=0, server_default="0")
    helpful_no = Column(Integer, nullable=False, default=0, server_default="0")
    created_at = Column(DateTime(timezone=True), server_default=func.now())
    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

    organization = relationship("Organization")
    knowledge = relationship("Knowledge")

    __table_args__ = (
        Index("ix_faqs_org_status", "organization_id", "status"),
        Index("ix_faqs_org_category", "organization_id", "category"),
        # Serves the public /a/{slug} lookup and enforces per-org uniqueness.
        # Multiple NULL slugs coexist (Postgres treats NULLs as distinct).
        Index("ix_faqs_org_slug", "organization_id", "slug", unique=True),
        # Serves the preserved-path lookup made for any URL no other public
        # route claimed, and enforces per-org uniqueness. NULLs coexist.
        Index("ix_faqs_org_url_path", "organization_id", "url_path", unique=True),
    )