"""ai-draft data model.

Per functional-design entities (unit: ai-draft): DraftBrief, DraftArticle,
DraftBundle, StatusMessage. Lightweight plain-data shapes owned by the
ai-draft library; per Contract 1/5 the DraftBundle is the per-article review
handoff.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from typing import Literal

ArticleKind = Literal["lead", "article", "filler", "wellwish"]
BundleStatus = Literal["drafted", "empty", "partial_error"]


@dataclass
class MastheadConfig:
    """Dynamic masthead/metadata input read from config.json (US7/Q3=A).

    Owned by the generator (functional-design), but carried here as a shape the
    ai-draft brief can reference for on-theme context (couple names, occasion).
    """

    title: str
    couple_names: str
    date_line: str
    issue_number: str
    volume: str


@dataclass
class DraftBrief:
    """The concise input ai-draft builds and hands to the cloud model (Q4=A)."""

    content_context: str
    requested_article_types: list[str] = field(default_factory=lambda: ["lead", "filler"])
    model: str = "deepseek-v4-flash:cloud"
    tone_instruction: str = (
        "Write warm, keepsake-appropriate newspaper copy for a wedding issue."
    )

    def __post_init__(self) -> None:
        if not self.content_context.strip():
            raise ValueError("content_context must be non-empty when a draft is requested")
        if not self.requested_article_types:
            raise ValueError("requested_article_types must contain at least one type")


@dataclass
class DraftArticle:
    """One drafted article, the per-article unit of the review handoff (Q2=A)."""

    article_id: str
    type: ArticleKind
    headline: str
    body: str
    byline: str = ""
    section: str = ""

    def round_trip(self) -> bool:
        """All string fields round-trip without dropping/escaping (NFR7-style)."""
        return (
            isinstance(self.article_id, str)
            and isinstance(self.type, str)
            and isinstance(self.headline, str)
            and isinstance(self.body, str)
            and isinstance(self.byline, str)
        )


@dataclass
class StatusMessage:
    """A clear, human-readable status note (Q3=A)."""

    code: str
    message: str


@dataclass
class DraftBundle:
    """The per-article review handoff (Contract 5). status=empty means the model
    was unreachable/failed and the generator proceeds without AI (Q3=A / BR2.1)."""

    draft_bundle_id: str
    articles: list[DraftArticle]
    generated_at: str
    status: BundleStatus = "drafted"
    status_message: StatusMessage | None = None

    def article(self, article_id: str) -> DraftArticle | None:
        """Return one article by id, keeping each article addressable (BR1.3)."""
        return next((a for a in self.articles if a.article_id == article_id), None)


def empty_draft_bundle(
    draft_bundle_id: str, generated_at: str, code: str, message: str
) -> DraftBundle:
    """A fail-soft empty DraftBundle with a clear StatusMessage (BR2.1, Q3=A)."""
    return DraftBundle(
        draft_bundle_id=draft_bundle_id,
        articles=[],
        generated_at=generated_at,
        status="empty",
        status_message=StatusMessage(code=code, message=message),
    )