main.go

package main

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"os/user"

	_ "github.com/mattn/go-sqlite3"
)

type Message struct {
	ID     string  `json:"id"`
	Date   int64   `json:"date"`
	FromMe bool    `json:"fromMe"`
	From   *Handle `json:"-"`
	Text   string  `json:"text"`
}

type Handle struct {
	ID   int    `json:"id"`
	Name string `json:"name"`
}

var handlerMap = make(map[int]*Handle)
var database *sql.DB

func scanMessage(row *sql.Rows) Message {
	var msg Message
	var handleID int
	row.Scan(&msg.ID, &msg.Date, &msg.FromMe, &handleID, &msg.Text)
	msg.From = handleById(handleID)

	return msg
}

func handleById(id int) *Handle {
	if handlerMap[id] != nil {
		return handlerMap[id]
	}

	query := fmt.Sprintf(`SELECT ROWID, id FROM handle WHERE ROWID = '%v'`, id)

	rows, err := database.Query(query)
	if err != nil {
		log.Panic(err)
	}
	defer rows.Close()

	var handle Handle
	rows.Scan(&handle.ID, &handle.Name)
	handlerMap[handle.ID] = &handle

	return &handle
}

func getMessages() (messages []Message) {
	query := fmt.Sprintln(`SELECT guid, date, is_from_me, handle_id, text FROM message ORDER BY date DESC LIMIT 5`)

	rows, err := database.Query(query)
	if err != nil {
		log.Panic(err)
	}
	defer rows.Close()

	for rows.Next() {
		message := scanMessage(rows)
		messages = append(messages, message)
	}

	return
}

func initDB(dir string) {
	var err error
	database, err = sql.Open("sqlite3", dir)

	if err != nil {
		log.Panic(err)
	}
}

func homeDir() string {
	usr, err := user.Current()
	if err != nil {
		log.Fatal(err)
	}

	return usr.HomeDir
}

func main() {
	dir := fmt.Sprintf("%s/Library/Messages/chat.db", homeDir())
	initDB(dir)

	messages := getMessages()

	jsonb, _ := json.MarshalIndent(messages, "", "  ")
	fmt.Println(string(jsonb))
}