package process

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"

	stdio "git.novox.be/novox/mesh-sdk/go"
)

// Ask reads the router's record of one of this process's module's own asks, under its own module and no
// other's (novox/hq ADR 0436 clause 4, ADR 0259 §3): by direct get on bucket, the same subject the tool
// runner reads (mesh-tools node-tools/internal/bus/seat.go ~300-345):
//
//	$JS.API.DIRECT.GET.KV_<bucket>.$KV.<bucket>.<module>.<id>
//
// bucket is the router's records bucket as the caller's own manifest names it (operator-channel's is
// messenger_asks in the controller's own test fixtures) — never hard-coded to one bucket here, since a
// process may read records of more than one seat's router. A missing, deleted or purged key is nil, not
// an error.
func (c *Conn) Ask(bucket, id string) (*stdio.StateEntry, error) {
	if err := checkAskID(id); err != nil {
		return nil, err
	}
	subject := "$JS.API.DIRECT.GET.KV_" + bucket + ".$KV." + bucket + "." + c.account.Module + "." + id
	ctx, cancel := context.WithTimeout(context.Background(), stateTimeout)
	defer cancel()
	reply, err := c.nc.RequestWithContext(ctx, subject, nil)
	if err != nil {
		return nil, fmt.Errorf("reading %s's ask %s from %s: %w", c.account.Module, id, bucket, err)
	}
	if status := reply.Header.Get("Status"); status == "404" {
		return nil, nil
	} else if status != "" {
		return nil, fmt.Errorf("the record %s.%s could not be read: %s %s", c.account.Module, id, status,
			reply.Header.Get("Description"))
	}
	if op := reply.Header.Get("KV-Operation"); op == "DEL" || op == "PURGE" {
		return nil, nil
	}
	var revision uint64
	if _, err := fmt.Sscan(reply.Header.Get("Nats-Sequence"), &revision); err != nil {
		return nil, fmt.Errorf("the record %s.%s carries no readable revision: %w", c.account.Module, id, err)
	}
	return &stdio.StateEntry{Key: c.account.Module + "." + id, Value: askValueOf(reply.Data), Revision: revision}, nil
}

// checkAskID refuses an id holding a dot or a wildcard before anything is sent: either would name a
// different key under the direct-get subject's own dot-joined path, never this one (novox/hq issue 1189
// AC2).
func checkAskID(id string) error {
	if id == "" || strings.ContainsAny(id, ".*>") {
		return fmt.Errorf("%q is not an ask id: an ask id holds no dot and no wildcard, naming one key and "+
			"no other", id)
	}
	return nil
}

// askValueOf is a record's raw bytes as JSON, quoting them when they are not already valid JSON
// (mesh-tools node-tools/internal/bus/state.go:351-357, valueOf).
func askValueOf(raw []byte) json.RawMessage {
	if len(raw) == 0 || !json.Valid(raw) {
		b, _ := json.Marshal(string(raw))
		return b
	}
	return json.RawMessage(append([]byte(nil), raw...))
}