package main

import (
	"bufio"
	"bytes"
	"crypto/tls"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"net/http/cookiejar"
	"os"
	"path"
	"sort"
	"strings"
	"time"

	"gopkg.in/yaml.v2"
)

type Client struct {
	http_client *http.Client
	base_url string
}

type Device struct {
	// Fields directly from UniFi
	Name string `json:"name"`
	MAC string `json:"mac"`

	// Constructed fields
	Neighbors map[string]*Device // all device peers
	Beyond map[string]*Device // device peers that we reach through this device
	Path []*Device

	// Intermediate data; ignore
	Ports []*Port `json:"port_table"`
}

type Port struct {
	LLDP []*LLDP `json:"lldp_table"`
}

type LLDP struct {
	MAC string `json:"lldp_chassis_id"`
	Port string `json:"lldp_port_id"`
	Name string `json:"lldp_system_name"`
}

type DeviceResp struct {
	Data []*Device `json:"data"`
}

func NewClient(base_url string) (*Client, error) {
	jar, err := cookiejar.New(nil)
	if err != nil {
		return nil, err
	}

	return &Client{
		http_client: &http.Client{
			Timeout: 5 * time.Second,
			Transport: &http.Transport{
				TLSClientConfig: &tls.Config{
					InsecureSkipVerify: true,
				},
			},
			Jar: jar,
		},
		base_url: base_url,
	}, nil
}

type Creds struct {
	Username string `json:"username"`
	Password string `json:"password"`
}

type ErrorResp struct {
	Errors []string
}

func (c *Client) Login() error {
	needSave := false

	creds, err := loadCreds()
	if err != nil {
		creds, err = promptCreds()
		if err != nil {
			return err
		}
		needSave = true
	}

	body, err := json.Marshal(creds)
	if err != nil {
		return err
	}

	req, err := http.NewRequest("POST", fmt.Sprintf("%s/api/auth/login", c.base_url), bytes.NewBuffer(body))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := c.http_client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		dec := json.NewDecoder(resp.Body)
		error_resp := ErrorResp{}
		err = dec.Decode(&error_resp)
		if err != nil {
			return err
		}
		return fmt.Errorf("Failed to log into UniFi with saved credentials (\"%s\"). Delete %s to prompt again.", error_resp.Errors[0], credPath())
	}

	log.Printf("Logged into UniFi as %s", creds.Username)

	if needSave {
		err = creds.Save()
		if err != nil {
			return err
		}
	}

	return nil
}

func (c *Client) ListDevices() (map[string]*Device, error) {
	req, err := http.NewRequest("GET", fmt.Sprintf("%s/proxy/network/api/s/default/stat/device", c.base_url), nil)

	resp, err := c.http_client.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		dec := json.NewDecoder(resp.Body)
		error_resp := ErrorResp{}
		err = dec.Decode(&error_resp)
		if err != nil {
			return nil, err
		}
		return nil, fmt.Errorf("%s", error_resp.Errors[0])
	}

	dec := json.NewDecoder(resp.Body)
	device_resp := DeviceResp{}
	err = dec.Decode(&device_resp)
	if err != nil {
		return nil, err
	}

	ret := map[string]*Device{}

	for _, dev := range device_resp.Data {
		dev.Neighbors = map[string]*Device{}
		dev.Beyond = map[string]*Device{}
		dev.Path = []*Device{}
		dev.MAC = strings.ToUpper(dev.MAC)

		if ret[dev.Name] != nil {
			return nil, fmt.Errorf("Duplicate UniFi device names: %s", dev.Name)
		}

		ret[dev.Name] = dev
	}

	// Second loop after the table is populated
	for _, dev := range ret {
		for _, port := range dev.Ports {
			for _, lldp := range port.LLDP {
				lldp.MAC = strings.ToUpper(lldp.MAC)

				neighbor := ret[lldp.Name]
				if neighbor == nil {
					continue
				}

				dev.Neighbors[neighbor.Name] = neighbor
			}
		}
		dev.Ports = nil
	}

	return ret, nil
}

func (d *Device) PathHop(path []*Device, visited map[string]*Device) {
	newPath := append(path, d)

	d.Path = newPath
	visited[d.Name] = d

	for _, neighbor := range d.Neighbors {
		if visited[neighbor.Name] != nil {
			// Cycle
			continue
		}

		d.Beyond[neighbor.Name] = neighbor
		neighbor.PathHop(newPath, visited)
	}
}

func (d *Device) LogHop(prefix string, last bool) {
	if last {
		log.Printf("%s└─ %s", prefix, d.Name)
	} else {
		log.Printf("%s├─ %s", prefix, d.Name)
	}

	names := []string{}
	for _, next := range d.Beyond {
		names = append(names, next.Name)
	}
	sort.Strings(names)

	i := 0
	for _, name := range names {
		next := d.Beyond[name]
		if last {
			next.LogHop(fmt.Sprintf("%s   ", prefix), i == len(names) - 1)
		} else {
			next.LogHop(fmt.Sprintf("%s│  ", prefix), i == len(names) - 1)
		}
		i++
	}
}

func loadCreds() (*Creds, error) {
	fh, err := os.OpenFile(credPath(), os.O_RDONLY, 0)
	if err != nil {
		return nil, err
	}
	defer fh.Close()

	dec := yaml.NewDecoder(fh)

	ret := &Creds{}

	err = dec.Decode(ret)
	if err != nil {
		return nil, err
	}

	return ret, nil
}

func promptCreds() (*Creds, error) {
	reader := bufio.NewReader(os.Stdin)

	fmt.Print("UniFi username: ")
	username, err := reader.ReadString('\n')
	if err != nil {
		return nil, err
	}

	fmt.Print("UniFi password: ")
	password, err := reader.ReadString('\n')
	if err != nil {
		return nil, err
	}

	return &Creds{
		Username: strings.TrimSuffix(username, "\n"),
		Password: strings.TrimSuffix(password, "\n"),
	}, nil
}

func (c *Creds) Save() error {
	fh, err := os.OpenFile(credPath(), os.O_WRONLY|os.O_CREATE, 0600)
	if err != nil {
		return err
	}
	defer fh.Close()

	enc := yaml.NewEncoder(fh)
	defer enc.Close()

	err = enc.Encode(c)
	if err != nil {
		return err
	}

	log.Printf("Saved credentials to %s", credPath())

	return nil
}

func credPath() string {
	return path.Join(os.Getenv("HOME"), ".netperfect.creds")
}