"""What the MODEL is asked to return.

Deliberately separate from `models.py`. The model never supplies `doc_id` (we
know it), never sets `extraction_status`, and never sets the conflict or diff
fields — validation owns those. **Asking a model for fields it cannot know is an
invitation to fabricate**, so the request schema is narrower than the stored one.

v2 narrowed it further, and every removal has a reason of that kind:

- **ids and links** (`term_id`, `formula_id`, `rule_id`, `domain_id`,
  `defining_formula_id`, `formula_ids`, `term_ids`, `variables[].term_id`) are
  minted deterministically. A model cannot produce a stable identifier — it has
  no memory of what it emitted last run — and `rule_id` being model-written was
  a real defect, not a style choice.
- **`domain` / `company`** were never in any prompt's field guide, so the model
  filled them purely by copying the worked examples, and neither was
  span-guarded — a wrong value was undetectable.
- **`formula_latex` on the glossary draft** duplicated the formula branch. One
  truth, one place; the glossary now references it.
- **`interpretation`** moved to the Interpretation Pack, reached via `term_id`.
"""

from __future__ import annotations

from typing import Literal

from pydantic import BaseModel, Field

from ..models import SubdomainEnum

RuleTypeDraft = Literal["interpretation", "calculation"]


class ProvenanceDraft(BaseModel):
    section_no: str | None = None
    page: int
    span: str


class GlossaryDraft(BaseModel):
    term: str
    full_name: str | None = None
    # The wording exactly as the document writes it, even when "wrong" — the
    # standard heads its section "Physical of Availability (PA)". Surfacing the
    # discrepancy is the point; normalising it hides a decision the expert owns.
    #
    # Still requested, though the stored value is taken deterministically from
    # the section heading: the model's answer is the fallback when no evidence
    # chunk carries a heading naming the term.
    source_wording: str | None = None
    definition: str | None = None
    subdomain_tags: list[SubdomainEnum] = Field(default_factory=list)
    provenance: ProvenanceDraft


class RuleDraft(BaseModel):
    # `rule_id` is NOT requested — it is minted from the document position. The
    # model previously wrote it as SCREAMING_SNAKE_CASE, which meant the same
    # rule could come back under a different id on the next run.
    rule_type: RuleTypeDraft = "calculation"
    statement: str | None = None
    condition: str | None = None
    consequence: str | None = None
    provenance: ProvenanceDraft


class VariableDraft(BaseModel):
    symbol: str
    meaning: str | None = None


class FormulaDraft(BaseModel):
    name: str | None = None
    formula_latex: str | None = None
    variables: list[VariableDraft] = Field(default_factory=list)
    unit: str | None = None
    provenance: ProvenanceDraft


class SummaryDraft(BaseModel):
    title: str | None = None
    # Located, not composed: the document's own statement of purpose, copied
    # verbatim, so the span check can prove it. See prompts/summary.txt.
    purpose_verbatim: str | None = None
    key_parameters: list[str] = Field(default_factory=list)
    provenance: ProvenanceDraft


DRAFTS = {
    "glossary": GlossaryDraft,
    "rule": RuleDraft,
    "formula": FormulaDraft,
    "summary": SummaryDraft,
}


def schema_for(branch: str) -> dict:
    return DRAFTS[branch].model_json_schema()