// © 2018 the slacktricks Authors under the WTFPL license. See AUTHORS for the list of authors.

package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"net/url"
	"os"
	"strconv"
)

var (
	token     = flag.String("token", "", "Slack API token")
	channel   = flag.String("channel", "", "Slack channel ID")
	limit     = flag.Int("limit", 100, "Number of items to return")
	byChannel = flag.Bool("byChannel", false, "Arrange data by channel (default by user)")
)

func main() {
	flag.Parse()

	users := getUsers()
	history := getHistory(*channel)

	if !*byChannel {
		for _, u := range users.Members {
			writeUser(history, u)
		}
	} else {
		writeChannel(history)
	}
}

func getUsers() userResp {
	users := userResp{}

	log.Printf("Getting users")
	body := mkReq("https://slack.com/api/users.list",
		"token", *token,
	)

	err := json.Unmarshal(body, &users)
	checkErr(err)

	return users
}

func getHistory(ch string) []histResp {
	history := []histResp{}
	cursor := ""
	for {
		log.Printf("Getting history cursor: '%s'", cursor)
		body := mkReq("https://slack.com/api/conversations.history",
			"token", *token,
			"channel", ch,
			"limit", strconv.Itoa(*limit),
			"cursor", cursor,
		)
		resp := histResp{}
		err := json.Unmarshal(body, &resp)
		checkErr(err)
		history = append(history, resp)
		if resp.ResponseMetadata.NextCursor == "" {
			break
		} else {
			cursor = resp.ResponseMetadata.NextCursor
		}
	}

	return history
}

func checkErr(err error) {
	if err != nil {
		log.Fatal(err)
	}
}

func mkReq(path string, arg ...string) []byte {
	if len(arg)%2 != 0 {
		log.Fatal("Bad request arg number.")
	}

	u, err := url.Parse(path)
	checkErr(err)

	q := u.Query()
	for i := 0; i < len(arg); i += 2 {
		key := arg[i]
		val := arg[i+1]
		if val != "" {
			q.Set(key, val)
		}
	}
	u.RawQuery = q.Encode()

	resp, err := http.Get(u.String())
	checkErr(err)

	body, err := ioutil.ReadAll(resp.Body)
	checkErr(err)

	return body
}

func writeChannel(history []histResp) {
	fname := *channel + ".json"
	f, err := os.Create(fname)
	checkErr(err)
	defer f.Close()

	j, err := json.Marshal(history)
	checkErr(err)
	f.Write(j)

	reactionCount := map[string]int{}
	for _, h := range history {
		for _, m := range h.Messages {
			if len(m.Reactions) > 0 {
				for _, r := range m.Reactions {
					reactionCount[r.Name] += r.Count
				}
			}
		}
	}

	fmt.Printf("%+v", reactionCount)
}

func writeUser(history []histResp, u user) {
	// open file and write shit out
	fname := u.Name + ".txt"
	id := u.ID

	f, err := os.OpenFile(fname, os.O_RDWR|os.O_CREATE, 0755)
	checkErr(err)
	defer f.Close()

	for _, h := range history {
		for _, m := range h.Messages {
			if m.User == id {
				fmt.Fprintf(f, "%s\n", m.Text)
			}
		}
	}
}

type histResp struct {
	Ok       bool `json:"ok"`
	Messages []struct {
		Type      string     `json:"type"`
		User      string     `json:"user"`
		Text      string     `json:"text"`
		Ts        string     `json:"ts"`
		Reactions []reaction `json:"reactions"`
	} `json:"messages"`
	HasMore          bool `json:"has_more"`
	PinCount         int  `json:"pin_count"`
	ResponseMetadata struct {
		NextCursor string `json:"next_cursor"`
	} `json:"response_metadata"`
}

type reaction struct {
	Name  string   `json:"name"`
	Users []string `json:"users"`
	Count int      `json:"count"`
}

type user struct {
	ID       string `json:"id"`
	TeamID   string `json:"team_id"`
	Name     string `json:"name"`
	Deleted  bool   `json:"deleted"`
	Color    string `json:"color"`
	RealName string `json:"real_name"`
	Tz       string `json:"tz"`
	TzLabel  string `json:"tz_label"`
	TzOffset int    `json:"tz_offset"`
	Profile  struct {
		AvatarHash            string `json:"avatar_hash"`
		StatusText            string `json:"status_text"`
		StatusEmoji           string `json:"status_emoji"`
		RealName              string `json:"real_name"`
		DisplayName           string `json:"display_name"`
		RealNameNormalized    string `json:"real_name_normalized"`
		DisplayNameNormalized string `json:"display_name_normalized"`
		Email                 string `json:"email"`
		Image24               string `json:"image_24"`
		Image32               string `json:"image_32"`
		Image48               string `json:"image_48"`
		Image72               string `json:"image_72"`
		Image192              string `json:"image_192"`
		Image512              string `json:"image_512"`
		Team                  string `json:"team"`
	} `json:"profile"`
	IsAdmin           bool `json:"is_admin"`
	IsOwner           bool `json:"is_owner"`
	IsPrimaryOwner    bool `json:"is_primary_owner"`
	IsRestricted      bool `json:"is_restricted"`
	IsUltraRestricted bool `json:"is_ultra_restricted"`
	IsBot             bool `json:"is_bot"`
	Updated           int  `json:"updated"`
	IsAppUser         bool `json:"is_app_user,omitempty"`
	Has2Fa            bool `json:"has_2fa"`
}

type userResp struct {
	Ok               bool   `json:"ok"`
	Members          []user `json:"members"`
	CacheTs          int    `json:"cache_ts"`
	ResponseMetadata struct {
		NextCursor string `json:"next_cursor"`
	} `json:"response_metadata"`
}