// Package tlog is the attest-reconciler's HTTP client for the Transparency Log
// (ADR-0005). Mirrors admin-api/internal/tlog.HTTPSubmitter byte-for-byte so
// resubmits from the reconciler collide with the admin-api's original log
// entry — the server's idempotency key covers both paths.
package tlog

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"time"

	"basicstack.de/proofedmesh/services/attest-reconciler/internal/attest"
)

type HTTPSubmitter struct {
	BaseURL     string
	Client      *http.Client
	TokenSource attest.TokenSource
}

type submitRequest struct {
	Envelope    attest.Envelope `json:"envelope"`
	ContentHash string          `json:"content_hash"`
}

func (s HTTPSubmitter) Submit(ctx context.Context, env attest.Envelope, contentHash string) (attest.LogReceipt, error) {
	if s.BaseURL == "" {
		return attest.LogReceipt{}, errors.New("tlog.HTTPSubmitter: BaseURL is empty")
	}
	cli := s.Client
	if cli == nil {
		cli = &http.Client{Timeout: 10 * time.Second}
	}
	body, err := json.Marshal(submitRequest{Envelope: env, ContentHash: contentHash})
	if err != nil {
		return attest.LogReceipt{}, fmt.Errorf("marshal: %w", err)
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, s.BaseURL+"/api/v1/log/entries", bytes.NewReader(body))
	if err != nil {
		return attest.LogReceipt{}, err
	}
	req.Header.Set("Content-Type", "application/json")
	if s.TokenSource != nil {
		tok, err := s.TokenSource.Token(ctx)
		if err != nil {
			return attest.LogReceipt{}, fmt.Errorf("token: %w", err)
		}
		req.Header.Set("Authorization", "Bearer "+tok)
	}
	resp, err := cli.Do(req)
	if err != nil {
		return attest.LogReceipt{}, err
	}
	defer resp.Body.Close()
	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 1<<20))
	switch resp.StatusCode {
	case http.StatusOK, http.StatusCreated:
	default:
		return attest.LogReceipt{}, fmt.Errorf("tlog: status %d: %s", resp.StatusCode, string(raw))
	}
	var out attest.LogReceipt
	if err := json.Unmarshal(raw, &out); err != nil {
		return attest.LogReceipt{}, fmt.Errorf("decode: %w", err)
	}
	if out.ContentHash != contentHash {
		return out, fmt.Errorf("tlog response content_hash %q != sent %q", out.ContentHash, contentHash)
	}
	if out.LogIndex < 0 {
		return out, fmt.Errorf("tlog response has negative log_index %d", out.LogIndex)
	}
	return out, nil
}