"""FastAPI surface for the hosted Phase Registry, Extension Registry
(WP-0006-T03), and Target Ledger append API (WP-0006-T04). Metrics (T05)
and Conversion Attestation (T06) are separate components per
`specs/TechnicalSpecificationDocument.md` §4.1 and are not implemented in
this module.

Every route delegates to `target_revenue.registry` / `target_revenue.ledger`;
this file's only job is HTTP framing (status codes, request/response shape,
bearer-token extraction), not conformance or chaining logic.
"""

from __future__ import annotations

import os
from typing import Any

from fastapi import Depends, FastAPI, HTTPException, Request
from psycopg import Connection
from psycopg_pool import ConnectionPool

from .. import attestation, ledger, metrics, registry
from . import keys

app = FastAPI(title="Target Revenue Trust Service — Registries", version="0.1.0")

_DATABASE_URL_ENV = "TRF_DATABASE_URL"


def get_pool() -> ConnectionPool:
    if not hasattr(app.state, "pool"):
        dsn = os.environ.get(_DATABASE_URL_ENV)
        if not dsn:
            raise RuntimeError(f"{_DATABASE_URL_ENV} is not set")
        app.state.pool = ConnectionPool(dsn, min_size=1, max_size=5, open=True)
    return app.state.pool


def get_signing_key():
    if not hasattr(app.state, "signing_key"):
        app.state.signing_key = keys.load_signing_key()
    return app.state.signing_key


def get_connection():
    pool = get_pool()
    with pool.connection() as conn:
        yield conn


def get_licensor(request: Request, conn: Connection = Depends(get_connection)) -> registry.Licensor:
    auth = request.headers.get("authorization", "")
    if not auth.lower().startswith("bearer "):
        raise HTTPException(status_code=401, detail="missing bearer token")
    token = auth.split(" ", 1)[1].strip()
    try:
        return registry.authenticate(conn, token)
    except registry.RegistrationError as exc:
        raise HTTPException(status_code=401, detail=str(exc)) from exc


@app.post("/phases", status_code=201)
def register_phase(
    manifest: dict[str, Any],
    licensor: registry.Licensor = Depends(get_licensor),
    conn: Connection = Depends(get_connection),
) -> dict[str, str]:
    try:
        registry.register_phase_manifest(conn, licensor, manifest)
    except registry.RegistrationError as exc:
        raise HTTPException(status_code=422, detail=str(exc)) from exc
    return {"phase_id": manifest["phase"]["id"], "status": "registered"}


@app.get("/phases/{phase_id}")
def read_phase(phase_id: str, conn: Connection = Depends(get_connection)) -> dict[str, Any]:
    manifest = registry.get_phase_manifest(conn, phase_id)
    if manifest is None:
        raise HTTPException(status_code=404, detail="phase not found")
    return manifest


@app.post("/extensions", status_code=201)
def register_extension(
    extension: dict[str, Any],
    licensor: registry.Licensor = Depends(get_licensor),
    conn: Connection = Depends(get_connection),
) -> dict[str, str]:
    try:
        registry.register_extension(conn, licensor, extension)
    except registry.RegistrationError as exc:
        raise HTTPException(status_code=422, detail=str(exc)) from exc
    return {
        "extension_id": extension["id"],
        "version": extension["version"],
        "status": "registered",
    }


@app.get("/extensions/{extension_id}/{version}")
def read_extension(
    extension_id: str, version: str, conn: Connection = Depends(get_connection)
) -> dict[str, Any]:
    result = registry.get_extension(conn, extension_id, version)
    if result is None:
        raise HTTPException(status_code=404, detail="extension not found")
    return result


@app.get("/public-key")
def read_public_key() -> dict[str, str]:
    """The Ed25519 public key ledger entry signatures verify against.

    Deliberately unauthenticated: an external verifier must be able to
    check a signature without trusting anything about this API's own
    access control (TrustServicePRD §3 point 2, offline verifiability).
    """
    return {"algorithm": "ed25519", "public_key_hex": keys.public_key_hex(get_signing_key())}


@app.post("/phases/{phase_id}/ledger", status_code=201)
def append_ledger_entry(
    phase_id: str,
    entry: dict[str, Any],
    licensor: registry.Licensor = Depends(get_licensor),
    conn: Connection = Depends(get_connection),
    signing_key=Depends(get_signing_key),
) -> dict[str, Any]:
    try:
        return ledger.append_entry(conn, licensor, phase_id, entry, signing_key)
    except registry.RegistrationError as exc:
        raise HTTPException(status_code=422, detail=str(exc)) from exc


@app.get("/phases/{phase_id}/ledger")
def read_ledger(
    phase_id: str, conn: Connection = Depends(get_connection)
) -> list[dict[str, Any]]:
    """Public: ledger facts are public per FR-10 (aggregate figures,
    confidential evidence *references* — not the evidence itself)."""
    if registry.get_phase_manifest(conn, phase_id) is None:
        raise HTTPException(status_code=404, detail="phase not found")
    return ledger.get_ledger(conn, phase_id)


@app.get("/phases/{phase_id}/metrics")
def read_metrics(
    phase_id: str, conn: Connection = Depends(get_connection)
) -> dict[str, Any]:
    """Public, unauthenticated per FR-9/FR-10 — see `target_revenue.metrics`
    for the fact/calculation/forecast labeling this response preserves."""
    manifest = registry.get_phase_manifest(conn, phase_id)
    if manifest is None:
        raise HTTPException(status_code=404, detail="phase not found")
    entries = ledger.get_ledger(conn, phase_id)
    return metrics.compute_metrics(manifest, entries, metrics.utcnow())


@app.get("/phases/{phase_id}/attestation")
def read_attestation(
    phase_id: str,
    conn: Connection = Depends(get_connection),
    signing_key=Depends(get_signing_key),
) -> dict[str, Any]:
    """Public, unauthenticated. Publishes (idempotently) the first time a
    conversion is observed, and simply returns the already-published
    record on every call after that — never regenerates, never requires
    this call to have happened for conversion to already be legally true
    (see target_revenue.attestation's module docstring)."""
    manifest = registry.get_phase_manifest(conn, phase_id)
    if manifest is None:
        raise HTTPException(status_code=404, detail="phase not found")
    entries = ledger.get_ledger(conn, phase_id)
    try:
        return attestation.publish_attestation(conn, manifest, entries, signing_key)
    except attestation.NotConvertedError as exc:
        raise HTTPException(status_code=404, detail=str(exc)) from exc