package client

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

	"git.franklin.lab/steve.cliff/pcli/model"
)

type Client struct {
	BaseURL    string
	APIKey     string
	HTTPClient *http.Client
	Logger     *slog.Logger
}

func NewClient(baseURL, apiKey string, logger *slog.Logger) *Client {
	transport := &http.Transport{
		MaxIdleConns:        10,
		MaxIdleConnsPerHost: 5,
		IdleConnTimeout:     30 * time.Second,
	}
	return &Client{
		BaseURL: baseURL,
		APIKey:  apiKey,
		HTTPClient: &http.Client{
			Timeout:   30 * time.Second,
			Transport: transport,
		},
		Logger: logger,
	}
}

func (c *Client) Do(ctx context.Context, method, path string, body any) (json.RawMessage, error) {
	start := time.Now()

	url := c.BaseURL + path

	var reqBody io.Reader
	if body != nil {
		jsonData, err := json.Marshal(body)
		if err != nil {
			return nil, fmt.Errorf("failed to marshal request body: %w", err)
		}
		reqBody = bytes.NewReader(jsonData)
	}

	req, err := http.NewRequestWithContext(ctx, method, url, reqBody)
	if err != nil {
		return nil, fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("x-api-key", c.APIKey)
	if body != nil {
		req.Header.Set("Content-Type", "application/json")
	}

	c.Logger.Debug("HTTP request",
		slog.String("method", method),
		slog.String("path", path),
	)

	resp, err := c.HTTPClient.Do(req)
	if err != nil {
		c.Logger.Warn("HTTP request failed",
			slog.String("method", method),
			slog.String("path", path),
			slog.String("error", err.Error()),
		)
		return nil, fmt.Errorf("HTTP request failed: %w", err)
	}
	defer resp.Body.Close()

	duration := time.Since(start)

	c.Logger.Debug("HTTP response",
		slog.String("method", method),
		slog.String("path", path),
		slog.Int("status", resp.StatusCode),
		slog.Duration("duration", duration),
	)

	respBody, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("failed to read response body: %w", err)
	}

	contentType := resp.Header.Get("Content-Type")
	if len(respBody) > 0 && !isJSONContentType(contentType) && respBody[0] == '<' {
		c.Logger.Warn("Non-JSON response received",
			slog.String("method", method),
			slog.String("path", path),
			slog.Int("status", resp.StatusCode),
			slog.String("content_type", contentType),
		)
		return nil, &model.APIError{
			StatusCode: resp.StatusCode,
			Message:    fmt.Sprintf("unexpected non-JSON response (content-type: %s) — endpoint may not exist", contentType),
		}
	}

	if resp.StatusCode >= 400 {
		apiErr := &model.APIError{
			StatusCode: resp.StatusCode,
			Message:    string(respBody),
		}

		var errResp map[string]any
		if json.Unmarshal(respBody, &errResp) == nil {
			if msg, ok := errResp["message"].(string); ok {
				apiErr.Message = msg
			} else if errMsg, ok := errResp["error"].(string); ok {
				apiErr.Message = errMsg
			}
		}

		c.Logger.Warn("API error",
			slog.String("method", method),
			slog.String("path", path),
			slog.Int("status", resp.StatusCode),
			slog.String("message", apiErr.Message),
		)

		return nil, apiErr
	}

	return json.RawMessage(respBody), nil
}

func (c *Client) DoNoBody(ctx context.Context, method, path string) (json.RawMessage, error) {
	return c.Do(ctx, method, path, nil)
}

func (c *Client) DoWithFallback(ctx context.Context, method, primary, fallback string, body any) (json.RawMessage, error) {
	data, err := c.Do(ctx, method, primary, body)
	if err != nil {
		if apiErr, ok := err.(*model.APIError); ok && apiErr.StatusCode == 404 {
			c.Logger.Debug("Primary path failed, trying fallback",
				slog.String("primary", primary),
				slog.String("fallback", fallback),
			)
			return c.Do(ctx, method, fallback, body)
		}
		return nil, err
	}
	return data, nil
}

func (c *Client) DoNoBodyWithFallback(ctx context.Context, method, primary, fallback string) (json.RawMessage, error) {
	return c.DoWithFallback(ctx, method, primary, fallback, nil)
}

func isJSONContentType(contentType string) bool {
	ct := strings.ToLower(strings.TrimSpace(contentType))
	return strings.HasPrefix(ct, "application/json") ||
		strings.HasPrefix(ct, "text/json")
}