package main

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

const sessionCookieName = "ufile_session"

type apiClient struct {
	host    string
	session string
	http    *http.Client
}

type apiError struct {
	Status  int
	Code    string
	Message string
}

func (e *apiError) Error() string { return e.Message }

type userResponse struct {
	ID                 uint      `json:"id"`
	Username           string    `json:"username"`
	CanManageUsers     bool      `json:"canManageUsers"`
	CanManageFiles     bool      `json:"canManageFiles"`
	CanUpload          bool      `json:"canUpload"`
	CanAdvancedUpload  bool      `json:"canAdvancedUpload"`
	MustChangePassword bool      `json:"mustChangePassword"`
	CreatedAt          time.Time `json:"createdAt"`
	UpdatedAt          time.Time `json:"updatedAt"`
}

type fileResponse struct {
	ID            uint       `json:"id"`
	Hash          string     `json:"hash"`
	Name          string     `json:"name"`
	MimeType      string     `json:"mimeType"`
	Size          int64      `json:"size"`
	ExpiresAt     *time.Time `json:"expiresAt"`
	MaxDownloads  *int       `json:"maxDownloads"`
	DownloadCount int        `json:"downloadCount"`
}

func newAPIClient(host, session string, timeout time.Duration) *apiClient {
	return &apiClient{host: host, session: session, http: &http.Client{Timeout: timeout}}
}

func (c *apiClient) newRequest(ctx context.Context, method, path string, body io.Reader) (*http.Request, error) {
	request, err := http.NewRequestWithContext(ctx, method, c.host+path, body)
	if err != nil {
		return nil, err
	}
	request.Header.Set("Accept", "application/json")
	request.Header.Set("User-Agent", "ufile-cli/"+version)
	if c.session != "" {
		request.AddCookie(&http.Cookie{Name: sessionCookieName, Value: c.session})
	}
	return request, nil
}

func (c *apiClient) doJSON(ctx context.Context, method, path string, requestBody, responseBody any) (*http.Response, error) {
	var body io.Reader
	if requestBody != nil {
		data, err := json.Marshal(requestBody)
		if err != nil {
			return nil, err
		}
		body = bytes.NewReader(data)
	}
	request, err := c.newRequest(ctx, method, path, body)
	if err != nil {
		return nil, err
	}
	if requestBody != nil {
		request.Header.Set("Content-Type", "application/json")
	}
	response, err := c.http.Do(request)
	if err != nil {
		return nil, err
	}
	defer response.Body.Close()
	if response.StatusCode < 200 || response.StatusCode >= 300 {
		return response, decodeAPIError(response)
	}
	if responseBody == nil || response.StatusCode == http.StatusNoContent {
		_, _ = io.Copy(io.Discard, response.Body)
		return response, nil
	}
	if err := json.NewDecoder(io.LimitReader(response.Body, 2<<20)).Decode(responseBody); err != nil {
		return response, fmt.Errorf("服务端返回了无效的 JSON: %w", err)
	}
	return response, nil
}

func decodeAPIError(response *http.Response) error {
	payload := struct {
		Error string `json:"error"`
		Code  string `json:"code"`
	}{}
	data, _ := io.ReadAll(io.LimitReader(response.Body, 1<<20))
	_ = json.Unmarshal(data, &payload)
	message := strings.TrimSpace(payload.Error)
	if message == "" {
		message = strings.TrimSpace(string(data))
	}
	if message == "" {
		message = response.Status
	}
	return &apiError{Status: response.StatusCode, Code: payload.Code, Message: message}
}