backend/app/api/bayesian.py

"""Direct (non-agent) Bayesian compute endpoints.

These are useful both as a fallback (when no API key is configured) and as a
fast path the frontend can call directly when the user is hand-driving the
workbench instead of talking to the Agent.
"""

from __future__ import annotations

from fastapi import APIRouter, HTTPException

from app.api.schemas import (
    BayesComputeRequest,
    BayesResultModel,
    SensitivityPointModel,
    SensitivityRequest,
    SensitivityResponse,
    bayes_result_to_model,
)
from app.domain.bayesian import compute, kde, sensitivity_analysis
from app.domain.report import render_markdown_report

router = APIRouter(prefix="/api/bayesian", tags=["bayesian"])


@router.post("/compute", response_model=BayesResultModel)
async def post_compute(req: BayesComputeRequest) -> BayesResultModel:
    try:
        result = compute(req.data, req.judgments, req.R)
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e)) from e
    return bayes_result_to_model(result)


@router.post("/sensitivity", response_model=SensitivityResponse)
async def post_sensitivity(req: SensitivityRequest) -> SensitivityResponse:
    try:
        points = sensitivity_analysis(req.data, req.judgments, req.r_values)
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e)) from e
    return SensitivityResponse(
        points=[
            SensitivityPointModel(R=p["R"], result=bayes_result_to_model(p["result"]))
            for p in points
        ]
    )


@router.post("/kde")
async def post_kde(req: BayesComputeRequest) -> dict:
    """Return the KDE curve for the dataset (200 points). Used by the
    PriorPosterior / KDE chart on the frontend."""
    try:
        pts = kde(req.data, n_points=200)
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e)) from e
    return {"points": pts}


@router.post("/report")
async def post_report(req: BayesComputeRequest) -> dict:
    """Compute + render a structured Markdown report in one call."""
    try:
        result = compute(req.data, req.judgments, req.R)
        sweep = sensitivity_analysis(req.data, req.judgments, [2.0, 5.0, 10.0, 20.0, 50.0])
    except ValueError as e:
        raise HTTPException(status_code=400, detail=str(e)) from e
    sens_rows = [
        {
            "R": p["R"],
            "posterior_mean": p["result"].posterior.stats.mean,
            "posterior_std": p["result"].posterior.stats.std,
            "ci95_lower": p["result"].posterior.stats.ci95_lower,
            "ci95_upper": p["result"].posterior.stats.ci95_upper,
        }
        for p in sweep
    ]
    md = render_markdown_report(
        result,
        scenario_name=req.scenario_name or "未命名情景",
        reference_case=req.reference_case or "",
        sensitivity_rows=sens_rows,
    )
    return {"markdown": md, "result": bayes_result_to_model(result).model_dump()}