package client

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"time"

	"git.wzray.com/homelab/hivemind/internal/types"
	"git.wzray.com/homelab/hivemind/internal/web/middleware"
)

type client struct {
	http       *http.Client
	middleware middleware.Middleware
}

var defaultClient *client

const timeout = time.Duration(2) * time.Second

func (c *client) makeRequest(method string, host string, path types.Path, data any, out any) error {
	var body io.Reader
	if data != nil {
		raw, err := json.Marshal(data)
		if err != nil {
			return fmt.Errorf("marshal body: %w", err)
		}
		body = bytes.NewReader(raw)
	}

	uri := (&url.URL{
		Scheme: "http",
		Host:   host,
		Path:   path.String(),
	}).String()

	r, err := http.NewRequest(method, uri, body)
	if err != nil {
		return fmt.Errorf("build http request: %w", err)
	}

	if body != nil {
		r.Header.Set("Content-Type", "application/json; charset=utf-8")
	}

	if err := c.middleware.Client(r); err != nil {
		return fmt.Errorf("apply middleware: %w", err)
	}

	resp, err := c.http.Do(r)
	if err != nil {
		return fmt.Errorf("send request: %w", err)
	}

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		b, _ := io.ReadAll(resp.Body)
		return fmt.Errorf("http %d: %s", resp.StatusCode, string(b))
	}

	defer resp.Body.Close()
	if out != nil {
		if err := json.NewDecoder(resp.Body).Decode(out); err != nil {
			return fmt.Errorf("decode body: %w", err)
		}
	}

	io.Copy(io.Discard, resp.Body)
	return nil
}

func Init(mw middleware.Middleware) {
	if defaultClient != nil {
		panic("web.client: Init called twice")
	}

	defaultClient = &client{
		http: &http.Client{
			Timeout: timeout,
		},
		middleware: mw,
	}
}

func request[Out any, In any](method string, host string, path types.Path, data In) (*Out, error) {
	out := &types.Response[Out]{}
	err := defaultClient.makeRequest(method, host, path, data, out)
	if err != nil {
		return nil, err
	}

	if !out.Ok {
		return nil, errors.New(out.Err)
	}

	return &out.Data, err
}

// TODO: out should not be a pointer
func Get[Out any](host string, path types.Path) (*Out, error) {
	return request[Out, any](http.MethodGet, host, path, nil)
}

// TODO: out should not be a pointer
func Post[Out any, In any](host string, path types.Path, data In) (*Out, error) {
	return request[Out](http.MethodPost, host, path, data)
}