package agentbridge

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

	"git.cin.su/m/Assistant/contracts/work"
)

var ErrUnavailable = errors.New("agent execution bridge unavailable")

type HTTPExecutor struct {
	URL    string
	Client *http.Client
}

func NewHTTPExecutor(url string, client *http.Client) (*HTTPExecutor, error) {
	url = strings.TrimSpace(url)
	if url == "" || !strings.HasPrefix(url, "http://") && !strings.HasPrefix(url, "https://") {
		return nil, ErrUnavailable
	}
	if client == nil {
		client = http.DefaultClient
	}
	return &HTTPExecutor{URL: strings.TrimRight(url, "/"), Client: client}, nil
}

func (e *HTTPExecutor) Execute(ctx context.Context, request work.AgentExecutionRequest) (work.AgentExecutionResult, error) {
	body, err := json.Marshal(request)
	if err != nil {
		return work.AgentExecutionResult{}, err
	}
	httpRequest, err := http.NewRequestWithContext(ctx, http.MethodPost, e.URL+"/v1/execute", bytes.NewReader(body))
	if err != nil {
		return work.AgentExecutionResult{}, err
	}
	httpRequest.Header.Set("Content-Type", "application/json")
	response, err := e.Client.Do(httpRequest)
	if err != nil {
		return work.AgentExecutionResult{}, fmt.Errorf("%w: %v", ErrUnavailable, err)
	}
	defer response.Body.Close()
	if response.StatusCode < 200 || response.StatusCode >= 300 {
		return work.AgentExecutionResult{}, fmt.Errorf("%w: status=%s", ErrUnavailable, response.Status)
	}
	decoder := json.NewDecoder(io.LimitReader(response.Body, 1<<20))
	var result work.AgentExecutionResult
	if err := decoder.Decode(&result); err != nil {
		return work.AgentExecutionResult{}, err
	}
	if result.State == "" || result.Summary == "" || result.ObservedAtUnixMillis < 1 {
		return work.AgentExecutionResult{}, errors.New("agent execution bridge returned invalid result")
	}
	return result, nil
}