package multitable

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

type Client struct {
	baseURL       string
	apiKey        string
	http          *http.Client
	mu            sync.Mutex
	sourceColumns map[uint64]string
}

func NewClient(baseURL, apiKey string, timeout time.Duration) *Client {
	return &Client{baseURL: strings.TrimRight(baseURL, "/"), apiKey: apiKey, http: &http.Client{Timeout: timeout}, sourceColumns: make(map[uint64]string)}
}

func (c *Client) Upsert(ctx context.Context, tableID uint64, sourceID string, data map[string]interface{}) error {
	sourceColumn, err := c.sourceColumn(ctx, tableID)
	if err != nil {
		return err
	}
	filters, err := json.Marshal([]map[string]interface{}{{"col": sourceColumn, "op": "eq", "val": sourceID}})
	if err != nil {
		return fmt.Errorf("encode filters: %w", err)
	}
	endpoint := c.endpoint("tables", fmt.Sprint(tableID), "records")
	u, err := url.Parse(endpoint)
	if err != nil {
		return fmt.Errorf("parse records endpoint: %w", err)
	}
	query := u.Query()
	query.Set("page", "1")
	query.Set("pageSize", "2")
	query.Set("filters", string(filters))
	u.RawQuery = query.Encode()

	var listed struct {
		Items []struct {
			ID uint64 `json:"id"`
		} `json:"items"`
	}
	if err := c.doJSON(ctx, http.MethodGet, u.String(), nil, &listed); err != nil {
		return err
	}
	body := map[string]interface{}{"data": data}
	if len(listed.Items) == 0 {
		return c.doJSON(ctx, http.MethodPost, endpoint, body, nil)
	}
	return c.doJSON(ctx, http.MethodPut, c.endpoint("tables", fmt.Sprint(tableID), "records", fmt.Sprint(listed.Items[0].ID)), body, nil)
}

func (c *Client) sourceColumn(ctx context.Context, tableID uint64) (string, error) {
	c.mu.Lock()
	if columnID, ok := c.sourceColumns[tableID]; ok {
		c.mu.Unlock()
		return columnID, nil
	}
	c.mu.Unlock()
	var columns []struct {
		ID   uint64 `json:"id"`
		Name string `json:"name"`
	}
	if err := c.doJSON(ctx, http.MethodGet, c.endpoint("tables", fmt.Sprint(tableID), "columns"), nil, &columns); err != nil {
		return "", err
	}
	for _, column := range columns {
		if column.Name == "来源ID" {
			columnID := fmt.Sprint(column.ID)
			c.mu.Lock()
			c.sourceColumns[tableID] = columnID
			c.mu.Unlock()
			return columnID, nil
		}
	}
	return "", fmt.Errorf("multitable table %d has no 来源ID column", tableID)
}

func (c *Client) endpoint(parts ...string) string {
	return c.baseURL + "/" + path.Join(parts...)
}

func (c *Client) doJSON(ctx context.Context, method, endpoint string, input interface{}, output interface{}) error {
	var body io.Reader
	if input != nil {
		encoded, err := json.Marshal(input)
		if err != nil {
			return fmt.Errorf("encode request: %w", err)
		}
		body = bytes.NewReader(encoded)
	}
	req, err := http.NewRequestWithContext(ctx, method, endpoint, body)
	if err != nil {
		return fmt.Errorf("build request: %w", err)
	}
	req.Header.Set("X-API-Key", c.apiKey)
	req.Header.Set("Accept", "application/json")
	if input != nil {
		req.Header.Set("Content-Type", "application/json")
	}
	resp, err := c.http.Do(req)
	if err != nil {
		return fmt.Errorf("call multitable API: %w", err)
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
	if err != nil {
		return fmt.Errorf("read multitable response: %w", err)
	}
	if resp.StatusCode < http.StatusOK || resp.StatusCode >= http.StatusMultipleChoices {
		return fmt.Errorf("multitable API returned %d: %s", resp.StatusCode, truncate(string(data), 512))
	}
	if output != nil && len(data) > 0 {
		if err := json.Unmarshal(data, output); err != nil {
			return fmt.Errorf("decode multitable response: %w", err)
		}
	}
	return nil
}

func truncate(value string, max int) string {
	if len(value) <= max {
		return value
	}
	return value[:max]
}