// Copyright 2025 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.

package api

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
)

func getJSON[Resp any](ctx context.Context, url string) (*Resp, error) {
	httpReq, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}
	return finishRequest[Resp](httpReq)
}

func postJSON[Req any, Resp any](ctx context.Context, url string, req *Req) (*Resp, error) {
	jsonBody, err := json.Marshal(req)
	if err != nil {
		return nil, err
	}
	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewBuffer(jsonBody))
	if err != nil {
		return nil, err
	}
	httpReq.Header.Set("Content-Type", "application/json")
	return finishRequest[Resp](httpReq)
}

func postMultiPartFile[Resp any](ctx context.Context, url string, reader io.Reader) (*Resp, error) {
	// TODO: this will work well only up to some size of the file. We need a pipe and a goroutine.
	body := &bytes.Buffer{}
	writer := multipart.NewWriter(body)
	part, err := writer.CreateFormFile("content", "content")
	if err != nil {
		return nil, fmt.Errorf("failed to create a form file part: %w", err)
	}
	if _, err := io.Copy(part, reader); err != nil {
		return nil, err
	}
	if err := writer.Close(); err != nil {
		return nil, err
	}
	httpReq, err := http.NewRequestWithContext(ctx, http.MethodPost, url, body)
	if err != nil {
		return nil, err
	}
	httpReq.Header.Set("Content-Type", writer.FormDataContentType())
	return finishRequest[Resp](httpReq)
}

func ReplyJSON[T any](w http.ResponseWriter, resp T) {
	w.Header().Set("Content-Type", "application/json")
	err := json.NewEncoder(w).Encode(resp)
	if err != nil {
		http.Error(w, "failed to serialize the response", http.StatusInternalServerError)
		return
	}
}

func ParseJSON[T any](w http.ResponseWriter, r *http.Request) *T {
	if r.Method != http.MethodPost {
		http.Error(w, "must be called via POST", http.StatusMethodNotAllowed)
		return nil
	}
	body, err := io.ReadAll(r.Body)
	if err != nil {
		http.Error(w, "failed to read body", http.StatusBadRequest)
		return nil
	}
	var data T
	err = json.Unmarshal(body, &data)
	if err != nil {
		http.Error(w, "invalid body", http.StatusBadRequest)
		return nil
	}
	return &data
}