package gonexapp

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

// OCSClient performs AppAPI-authenticated OCS requests with format=json.
type OCSClient struct {
	Cred   Credentials
	Client *http.Client
}

func (c OCSClient) httpClient() *http.Client {
	if c.Client != nil {
		return c.Client
	}
	return http.DefaultClient
}

// URL builds an OCS URL under /ocs/v2.php with format=json.
func (c OCSClient) URL(path string) string {
	base := strings.TrimRight(c.Cred.BaseURL, "/")
	path = strings.TrimPrefix(path, "/")
	return base + "/ocs/v2.php/" + path + "?format=json"
}

// Call performs method against path with an optional JSON body and returns the response body
// after verifying it is valid JSON. Non-2xx responses return an error including the status.
func (c OCSClient) Call(method, path string, body []byte) ([]byte, error) {
	var reader io.Reader
	if len(body) > 0 {
		reader = bytes.NewReader(body)
	}
	req, err := http.NewRequest(method, c.URL(path), reader)
	if err != nil {
		return nil, err
	}
	if len(body) > 0 {
		req.Header.Set("Content-Type", "application/json")
	}
	for k, vs := range c.Cred.AuthHeaders() {
		for _, v := range vs {
			req.Header.Set(k, v)
		}
	}
	res, err := c.httpClient().Do(req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()
	raw, err := io.ReadAll(res.Body)
	if err != nil {
		return nil, err
	}
	if res.StatusCode >= 300 {
		return nil, fmt.Errorf("ocs %s %s: %s", method, path, res.Status)
	}
	if !json.Valid(raw) {
		return nil, fmt.Errorf("ocs %s %s: response is not JSON", method, path)
	}
	return raw, nil
}