package stdlib

import (
	"context"
	"fmt"
	"io"
	"maps"
	"net/http"
	"strings"

	"reichard.io/poiesis/internal/functions"
)

func init() {
	functions.RegisterAsyncFunction("fetch", Fetch)
}

type FetchArgs struct {
	Input string       `json:"input"`
	Init  *RequestInit `json:"init,omitempty"`
}

func (f FetchArgs) Validate() error {
	return nil
}

type RequestInit struct {
	Method  string            `json:"method,omitempty"`
	Headers map[string]string `json:"headers,omitempty"`
	Body    *string           `json:"body,omitempty"`
}

func (o *RequestInit) Validate() error {
	return nil
}

type Response struct {
	OK      bool              `json:"ok"`
	Status  int               `json:"status"`
	Body    string            `json:"body"`
	Headers map[string]string `json:"headers"`
}

func Fetch(ctx context.Context, args FetchArgs) (Response, error) {
	// Set Default Method and Headers
	method := "GET"
	headers := make(map[string]string)

	// Apply Init Options
	if args.Init != nil {
		if args.Init.Method != "" {
			method = args.Init.Method
		}
		if args.Init.Headers != nil {
			maps.Copy(headers, args.Init.Headers)
		}
	}

	// Create Request
	req, err := http.NewRequestWithContext(ctx, method, args.Input, nil)
	if err != nil {
		return Response{}, fmt.Errorf("failed to create request: %w", err)
	}

	// Set Request Headers
	for k, v := range headers {
		req.Header.Set(k, v)
	}

	// Execute Request
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return Response{}, fmt.Errorf("failed to fetch: %w", err)
	}
	defer func() {
		_ = resp.Body.Close()
	}()

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

	// Collect Response Headers
	resultHeaders := make(map[string]string)
	for key, values := range resp.Header {
		if len(values) > 0 {
			val := values[0]
			resultHeaders[key] = val
			resultHeaders[strings.ToLower(key)] = val
		}
	}

	// Return Response
	return Response{
		OK:      resp.StatusCode >= 200 && resp.StatusCode < 300,
		Status:  resp.StatusCode,
		Body:    string(body),
		Headers: resultHeaders,
	}, nil
}