package pay007

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

const defaultUserAgent = "007pay-go-sdk/1.0"

type Client struct {
	baseURL    string
	pid        string
	secret     string
	httpClient *http.Client
	userAgent  string
}

type Option func(*Client)

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

func WithTimeout(timeout time.Duration) Option {
	return func(c *Client) {
		if timeout > 0 {
			c.httpClient.Timeout = timeout
		}
	}
}

func WithUserAgent(userAgent string) Option {
	return func(c *Client) {
		if strings.TrimSpace(userAgent) != "" {
			c.userAgent = userAgent
		}
	}
}

func NewClient(baseURL, pid, secret string, opts ...Option) (*Client, error) {
	baseURL = strings.TrimRight(strings.TrimSpace(baseURL), "/")
	if baseURL == "" {
		return nil, errors.New("baseURL is required")
	}
	if _, err := url.ParseRequestURI(baseURL); err != nil {
		return nil, fmt.Errorf("invalid baseURL: %w", err)
	}
	if strings.TrimSpace(pid) == "" {
		return nil, errors.New("pid is required")
	}
	if strings.TrimSpace(secret) == "" {
		return nil, errors.New("secret is required")
	}

	c := &Client{
		baseURL: baseURL,
		pid:     pid,
		secret:  secret,
		httpClient: &http.Client{
			Timeout: 15 * time.Second,
		},
		userAgent: defaultUserAgent,
	}
	for _, opt := range opts {
		opt(c)
	}
	return c, nil
}

func (c *Client) Sign(params map[string]string) string {
	return BuildSign(params, c.secret)
}

func (c *Client) Verify(params map[string]string) bool {
	return VerifySign(params, c.secret)
}

func (c *Client) Submit(ctx context.Context, req SubmitRequest) (*SubmitResponse, error) {
	var out SubmitResponse
	if err := c.doSigned(ctx, http.MethodPost, "/api/pay/submit", req.params(), &out); err != nil {
		return nil, err
	}
	return &out, nil
}

func (c *Client) Query(ctx context.Context, req QueryRequest) (*QueryResponse, error) {
	var out QueryResponse
	if err := c.doSigned(ctx, http.MethodGet, "/api/pay/query", req.params(), &out); err != nil {
		return nil, err
	}
	return &out, nil
}

func (c *Client) Refund(ctx context.Context, req RefundRequest) (*RefundResponse, error) {
	var out RefundResponse
	if err := c.doSigned(ctx, http.MethodPost, "/api/pay/refund", req.params(), &out); err != nil {
		return nil, err
	}
	return &out, nil
}

func (c *Client) Orders(ctx context.Context, req OrdersRequest) (*OrdersResponse, error) {
	var out OrdersResponse
	if err := c.doSigned(ctx, http.MethodGet, "/api/pay/orders", req.params(), &out); err != nil {
		return nil, err
	}
	return &out, nil
}

func (c *Client) Manual(ctx context.Context, req ManualRequest) (*ManualResponse, error) {
	var out ManualResponse
	if err := c.doSigned(ctx, http.MethodPost, "/api/pay/manual", req.params(), &out); err != nil {
		return nil, err
	}
	return &out, nil
}

func (c *Client) Stats(ctx context.Context, req StatsRequest) (*StatsResponse, error) {
	var out StatsResponse
	if err := c.doSigned(ctx, http.MethodGet, "/api/pay/stats", req.params(), &out); err != nil {
		return nil, err
	}
	return &out, nil
}

func (c *Client) doSigned(ctx context.Context, method, path string, params map[string]string, out any) error {
	signed := compactParams(params)
	signed["pid"] = c.pid
	signed["sign_type"] = "MD5"
	signed["sign"] = BuildSign(signed, c.secret)

	values := url.Values{}
	for k, v := range signed {
		values.Set(k, v)
	}

	endpoint := c.baseURL + path
	var body io.Reader
	if method == http.MethodGet {
		endpoint += "?" + values.Encode()
	} else {
		body = bytes.NewBufferString(values.Encode())
	}

	httpReq, err := http.NewRequestWithContext(ctx, method, endpoint, body)
	if err != nil {
		return err
	}
	httpReq.Header.Set("Accept", "application/json")
	httpReq.Header.Set("User-Agent", c.userAgent)
	if method != http.MethodGet {
		httpReq.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	}

	resp, err := c.httpClient.Do(httpReq)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	respBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	var envelope struct {
		Code    int             `json:"code"`
		Message string          `json:"message"`
		Data    json.RawMessage `json:"data"`
	}
	if err := json.Unmarshal(respBody, &envelope); err != nil {
		return &APIError{
			HTTPStatus: resp.StatusCode,
			Code:       0,
			Message:    "invalid json response: " + err.Error(),
			Body:       string(respBody),
		}
	}

	if resp.StatusCode < 200 || resp.StatusCode >= 300 || envelope.Code != 200 {
		return &APIError{
			HTTPStatus: resp.StatusCode,
			Code:       envelope.Code,
			Message:    envelope.Message,
			Body:       string(respBody),
		}
	}

	if out == nil || len(envelope.Data) == 0 || string(envelope.Data) == "null" {
		return nil
	}
	if err := json.Unmarshal(envelope.Data, out); err != nil {
		return &APIError{
			HTTPStatus: resp.StatusCode,
			Code:       envelope.Code,
			Message:    "invalid data response: " + err.Error(),
			Body:       string(respBody),
		}
	}
	return nil
}

type APIError struct {
	HTTPStatus int
	Code       int
	Message    string
	Body       string
}

func (e *APIError) Error() string {
	if e == nil {
		return ""
	}
	return fmt.Sprintf("007pay api error: http=%d code=%d message=%s", e.HTTPStatus, e.Code, e.Message)
}

func compactParams(params map[string]string) map[string]string {
	out := make(map[string]string, len(params))
	for k, v := range params {
		if strings.TrimSpace(k) == "" || v == "" {
			continue
		}
		out[k] = v
	}
	return out
}

func itoa(v int) string {
	return strconv.Itoa(v)
}