package orbit

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

// Options 配置传输与命名空间凭据；健康查询不使用凭据。
type Options struct {
	HTTPClient *http.Client
	Token      string
}
type Client struct {
	baseURL string
	http    *http.Client
	token   string
}
type Health struct {
	Status string `json:"status"`
	Scope  string `json:"scope,omitempty"`
}

// VersionInfo 描述服务构建身份和当前协议版本，不包含主机、数据库或租户信息。
type VersionInfo struct {
	Version               string `json:"version"`                 // Version 发布版本或本地开发标识。
	Revision              string `json:"revision"`                // Revision 不可变源码提交标识。
	BuiltAt               string `json:"built_at"`                // BuiltAt 构建时间。
	GoVersion             string `json:"go_version"`              // GoVersion 编译器版本。
	HTTPProtocolVersion   string `json:"http_protocol_version"`   // HTTPProtocolVersion HTTP接口主版本。
	WorkerProtocolVersion string `json:"worker_protocol_version"` // WorkerProtocolVersion Worker WebSocket子协议版本。
	EventProtocolVersion  string `json:"event_protocol_version"`  // EventProtocolVersion Event WebSocket子协议版本。
	WorkflowSchemaVersion int    `json:"workflow_schema_version"` // WorkflowSchemaVersion 流程定义结构版本。
}

// HTTPError exposes the status code without including sensitive response bodies.
type HTTPError struct{ StatusCode int }

func (e *HTTPError) Error() string { return fmt.Sprintf("orbit returned HTTP %d", e.StatusCode) }

func NewClient(baseURL string, opts Options) (*Client, error) {
	u, err := url.Parse(baseURL)
	if err != nil || u == nil || u.Host == "" || (u.Scheme != "http" && u.Scheme != "https") || u.User != nil || u.RawQuery != "" || u.Fragment != "" {
		return nil, errors.New("Orbit base URL must be absolute HTTP(S), without credentials, query or fragment")
	}
	if len(opts.Token) > 1024 || strings.ContainsAny(opts.Token, " \t\r\n") {
		return nil, errors.New("invalid Orbit token")
	}
	client := opts.HTTPClient
	if client == nil {
		client = &http.Client{Timeout: 10 * time.Second}
	}
	clone := *client
	// Do not silently forward requests to another origin through redirects.
	clone.CheckRedirect = func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse }
	return &Client{baseURL: strings.TrimRight(u.String(), "/"), http: &clone, token: opts.Token}, nil
}
func (c *Client) Liveness(ctx context.Context) (Health, error) { return c.health(ctx, "/health/live") }
func (c *Client) Readiness(ctx context.Context) (Health, error) {
	return c.health(ctx, "/health/ready")
}

// Version returns build and protocol identity from the unauthenticated version endpoint.
func (c *Client) Version(ctx context.Context) (VersionInfo, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+"/version", nil)
	if err != nil {
		return VersionInfo{}, err
	}
	req.Header.Set("Accept", "application/json")
	response, err := c.http.Do(req)
	if err != nil {
		return VersionInfo{}, err
	}
	defer response.Body.Close()
	if response.StatusCode != http.StatusOK {
		return VersionInfo{}, &HTTPError{StatusCode: response.StatusCode}
	}
	const maxBody = 16 << 10
	body, err := io.ReadAll(io.LimitReader(response.Body, maxBody+1))
	if err != nil {
		return VersionInfo{}, err
	}
	if len(body) > maxBody {
		return VersionInfo{}, errors.New("Orbit version response exceeds limit")
	}
	var info VersionInfo
	if err := json.Unmarshal(body, &info); err != nil {
		return VersionInfo{}, fmt.Errorf("decode Orbit version response: %w", err)
	}
	if info.Version == "" || info.HTTPProtocolVersion == "" || info.WorkerProtocolVersion == "" || info.EventProtocolVersion == "" || info.WorkflowSchemaVersion == 0 {
		return VersionInfo{}, errors.New("Orbit version response is missing identity")
	}
	return info, nil
}

func (c *Client) health(ctx context.Context, path string) (Health, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+path, nil)
	if err != nil {
		return Health{}, err
	}
	req.Header.Set("Accept", "application/json")
	response, err := c.http.Do(req)
	if err != nil {
		return Health{}, err
	}
	defer response.Body.Close()
	if response.StatusCode != http.StatusOK {
		return Health{}, &HTTPError{StatusCode: response.StatusCode}
	}
	const maxBody = 16 << 10
	body, err := io.ReadAll(io.LimitReader(response.Body, maxBody+1))
	if err != nil {
		return Health{}, err
	}
	if len(body) > maxBody {
		return Health{}, errors.New("Orbit health response exceeds limit")
	}
	var health Health
	if err := json.Unmarshal(body, &health); err != nil {
		return Health{}, fmt.Errorf("decode Orbit health response: %w", err)
	}
	if health.Status == "" {
		return Health{}, errors.New("Orbit health response is missing status")
	}
	return health, nil
}