// Package apiclient is a thin HTTP client for the Control API's /api/v1
// surface, shared by the validator-agent and prober binaries. Neither
// binary talks to the database directly — this is their only channel to
// shared state, keeping both genuinely stateless.
package apiclient

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

type Client struct {
	BaseURL    string
	HTTPClient *http.Client
	// Token, when non-empty, is sent as "Authorization: Bearer <Token>" on
	// every request to the Control API.
	Token string
}

func New(baseURL string, timeout time.Duration) *Client {
	return &Client{BaseURL: baseURL, HTTPClient: &http.Client{Timeout: timeout}}
}

// Do issues a JSON request and decodes a JSON response into out (if
// non-nil). A 204 response is treated as "no content" and out is left
// untouched, with ok=false — used for the assignment poll's empty case.
func (c *Client) Do(ctx context.Context, method, path string, body, out interface{}) (ok bool, err error) {
	var reader io.Reader
	if body != nil {
		b, err := json.Marshal(body)
		if err != nil {
			return false, fmt.Errorf("marshal request: %w", err)
		}
		reader = bytes.NewReader(b)
	}
	req, err := http.NewRequestWithContext(ctx, method, c.BaseURL+path, reader)
	if err != nil {
		return false, fmt.Errorf("build request: %w", err)
	}
	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}
	if c.Token != "" {
		req.Header.Set("Authorization", "Bearer "+c.Token)
	}

	resp, err := c.HTTPClient.Do(req)
	if err != nil {
		return false, fmt.Errorf("%s %s: %w", method, path, err)
	}
	defer resp.Body.Close()

	if resp.StatusCode == http.StatusNoContent {
		return false, nil
	}
	respBody, _ := io.ReadAll(resp.Body)
	if resp.StatusCode >= 300 {
		return false, fmt.Errorf("%s %s: status %d: %s", method, path, resp.StatusCode, string(respBody))
	}
	if out != nil && len(respBody) > 0 {
		if err := json.Unmarshal(respBody, out); err != nil {
			return false, fmt.Errorf("%s %s: decode response: %w", method, path, err)
		}
	}
	return true, nil
}