from __future__ import annotations

import secrets
import time

from .asking import ask_state
from .errors import Conflict, Missing, ToolError
from .fields import decode, expect, field
from .records import digest, shown
from .register import REGISTER, operator_rows, read_register, runnable
from .rules import rule_matches
from .signed import ask_signed, operator_signed, review_signed, signing

BATCH_LIMIT = 100
INBOX_KINDS = ("review", "ask", "decision", "operator")
VERBS = ("approve", "reject")


class Approving:
    def keys(self) -> list[dict]:
        try:
            entries = signing.load_pinned(self.approvers)
        except signing.Refused:
            return []
        return [{"id": entry["id"], "alg": signing.ALGORITHMS[entry["alg"]]} for entry in entries]

    def covered(self, proof: object, signed: list[dict], now: float) -> dict | None:
        """Args:
            proof: {"payload", "assertion"} from the page, or None.
            signed: the executor items the approval must list.
            now: the current time in epoch seconds.

        Returns:
            The proof to relay, None when nothing needs a signature. The hub
            checks the shape only; the executors verify the signature.
        """
        if not signed:
            if proof is not None:
                raise ToolError("proof must be null when no item needs a signature")
            return None
        if not isinstance(proof, dict):
            raise ToolError("nicht signiert: an approval of an ask, review or operator command needs the passkey signature")
        expect(proof, ("payload", "assertion"))
        try:
            payload = signing.checked_approval(proof["payload"], now)
        except signing.Refused as error:
            raise ToolError(f"proof: {error}") from None
        if not isinstance(proof["assertion"], dict) or any(signing.item_hash(item) not in payload["items"] for item in signed):
            raise ToolError("proof must carry the assertion and list every approved item")
        return {"payload": payload, "assertion": proof["assertion"]}

    def automate(self, kind_name: str, record: dict, subject: dict) -> None:
        now = time.time()
        rule = next((rule for rule in self.rules.listed() if rule_matches(rule, kind_name, subject, now)), None)
        if rule is None:
            return
        title = {"review": record.get("title"), "ask": f"{record.get('tool')} {record.get('command')}", "decision": record.get("question")}[kind_name]
        signed = None if kind_name == "decision" else subject["item"]
        item = {"kind": kind_name, "id": record["id"], "verb": "approve", "label": record.get("recommended", ""), "sha256": "", "title": shown(title)[:200], "gate": record.get("gate", ""), "signed": signed}
        batch = self.batches.add([item], f"rule:{rule['id']}", rule.get("proof"), self.apply)
        words = f"{rule['kind']} {rule['tool']} {rule['pattern']}".replace("  ", " ")
        self.log.add({"kind": "rule", "title": f"Regel gibt frei: {item['title']}", "text": words, "ref": {"rule": rule["id"], "batch": batch["id"], "item": item["id"]}})

    def apply(self, batch: dict) -> None:
        for item in batch["items"]:
            try:
                outcome = self.settle_item(item, batch["proof"] if item["signed"] is not None else None)
            except (OSError, ToolError) as error:
                outcome = f"fehlgeschlagen: {error}"
            verb = "Freigabe" if item["verb"] == "approve" else "Ablehnung"
            label = f" → {item['label']}" if item["label"] else ""
            ref = {"kind": item["kind"], "id": item["id"], "verb": item["verb"], "source": batch["source"], "outcome": outcome}
            self.log.add({"kind": "approval", "title": f"{verb} {item['kind']}: {item['title']}{label}", "text": f"{outcome} ({batch['source']})", "ref": ref})

    def settle_item(self, item: dict, proof: dict | None) -> str:
        approve = item["verb"] == "approve"
        if item["kind"] == "operator":
            return self.queue_job(item, proof)
        if item["kind"] == "ask":
            record = self.asks.get(item["id"])
            if record is None or ask_state(record, time.time())["status"] == "expired":
                return "abgelaufen"
            record, changed = self.asks.decide(item["id"], {"status": "allowed" if approve else "denied", "proof": proof})
        elif item["kind"] == "review":
            record, changed = self.reviews.decide(item["id"], {"status": "approved" if approve else "rejected", "proof": proof})
        else:
            record, changed = self.decisions.decide(item["id"], {"status": "decided", "choice": item["label"]})
        if record is None:
            return "unbekannt"
        return record["status"] if changed else f"schon {record['status']}"

    def item_of(self, raw: object, tasks: dict[str, dict]) -> dict:
        if not isinstance(raw, dict):
            raise ToolError("every item must be an object with kind, id, verb, label and sha256")
        expect(raw, ("kind", "id", "verb", "label", "sha256"))
        kind_name, verb = raw["kind"], raw["verb"]
        if kind_name not in INBOX_KINDS or verb not in VERBS or not isinstance(raw["label"], str) or not isinstance(raw["sha256"], str):
            raise ToolError(f"kind must be one of {', '.join(INBOX_KINDS)}, verb approve or reject, label and sha256 text")
        if kind_name == "operator":
            row = next((row for row in operator_rows(tasks) if row["task"] == raw["id"]), None)
            if row is None:
                raise Missing(str(raw["id"]))
            if verb != "approve" or not runnable(row):
                raise ToolError("an operator row is approved only, and only when it holds a directory and a command")
            if digest(row["command"]) != raw["sha256"]:
                raise Conflict({"id": row["task"], "status": "changed"})
            if row["task"] in self.open_jobs():
                raise Conflict({"id": row["task"], "status": "queued"})
            return {"kind": kind_name, "id": row["task"], "verb": verb, "label": "", "sha256": raw["sha256"], "title": row["command"][:200], "gate": "", "signed": operator_signed(row)}
        item_id = field(raw, "id")
        record = {"review": self.reviews, "ask": self.asks, "decision": self.decisions}[kind_name].get(item_id)
        if record is None:
            raise Missing(item_id)
        status = ask_state(record, time.time())["status"] if kind_name == "ask" else record["status"]
        if status != "pending":
            raise Conflict({"id": item_id, "status": status})
        label = ""
        if kind_name == "decision":
            if verb != "approve" or raw["label"] not in [option["label"] for option in record["options"]]:
                raise ToolError("a decision is approved with one of its option labels")
            label = raw["label"]
        title = {"review": record.get("title"), "ask": f"{record.get('tool')} {record.get('command')}", "decision": record.get("question")}[kind_name]
        signed = None
        if verb == "approve" and kind_name != "decision":
            signed = ask_signed(record) if kind_name == "ask" else review_signed(record)
        return {"kind": kind_name, "id": item_id, "verb": verb, "label": label, "sha256": "", "title": shown(title)[:200], "gate": record.get("gate", ""), "signed": signed}

    def checked(self, raw: object) -> list[dict]:
        if not isinstance(raw, list) or not 1 <= len(raw) <= BATCH_LIMIT:
            raise ToolError(f"items must be a list of 1 to {BATCH_LIMIT} objects")
        tasks = read_register(self.council / REGISTER)
        items = [self.item_of(entry, tasks) for entry in raw]
        keys = [(item["kind"], item["id"]) for item in items]
        if len(set(keys)) != len(keys):
            raise ToolError("items must be distinct")
        if len(items) > 1 and any(item["kind"] == "review" and item["verb"] == "approve" and item["gate"] != "pass" for item in items):
            raise ToolError("a review whose gate is not green is approved only on its own")
        if any(self.batches.holds(kind_name, item_id) for kind_name, item_id in keys):
            raise Conflict({"status": "held"})
        return items

    def sign(self, body: bytes) -> dict:
        payload = decode(body)
        expect(payload, ("items",))
        hashes = [signing.item_hash(item["signed"]) for item in self.checked(payload["items"]) if item["signed"] is not None]
        credentials = [key["id"] for key in self.keys()]
        if not hashes:
            return {"payload": None, "challenge": None, "credentials": credentials}
        request = signing.approval_payload(hashes, secrets.token_hex(16), int(time.time()) + signing.LIFETIME)
        return {"payload": request, "challenge": signing.challenge(request), "credentials": credentials}

    def approve(self, body: bytes) -> dict:
        payload = decode(body)
        expect(payload, ("items", "proof"))
        items = self.checked(payload["items"])
        proof = self.covered(payload["proof"], [item["signed"] for item in items if item["signed"] is not None], time.time())
        return self.batches.add(items, "operator", proof, self.apply)

    def undo(self, batch_id: str) -> dict:
        batch = self.batches.undo(batch_id)
        titles = ", ".join(item["title"][:80] for item in batch["items"])
        self.log.add({"kind": "approval", "title": f"Rückgängig: {titles}", "text": batch["source"], "ref": {"batch": batch_id}})
        return {"id": batch_id, "status": "undone"}