package main

import (
	"database/sql"
	"errors"
	"fmt"
	"log"
	"net/http"
	"os"

	"github.com/go-sql-driver/mysql"

	"github.com/gin-contrib/cors"
	"github.com/gin-gonic/gin"
)

var db *sql.DB

// Emoji counts for each post are retrieved in this format
type EmojiCount struct {
	Emoji      string
	TotalCount int
}

// Emojis' order should be like this
var emojis = [6]string{"👍", "👎", "😀", "😑", "🤢", "👀"}

// Get the emoji counts foe a given post id
func countEmojis(postId string) ([]EmojiCount, error) {
	emojiList := []EmojiCount{}
	// This will hold the total counts for each emoji
	// for a given post
	var emojiCounter = map[string]int{
		"👍": 0,
		"👎": 0,
		"😀": 0,
		"😑": 0,
		"🤢": 0,
		"👀": 0,
	}

	// Get the emoji counts for each emoji
	rows, err := db.Query("SELECT emoji, COUNT(*) FROM emoji_clicks WHERE post_id = ? GROUP BY emoji;", postId)
	if err != nil {
		return emojiList, errors.New("couldn't get emoji counts")
	}
	defer rows.Close()

	// Read the rows and update the counter
	for rows.Next() {
		var ec EmojiCount
		if err := rows.Scan(&ec.Emoji, &ec.TotalCount); err != nil {
			return emojiList, errors.New("DB results couldn't read")
		}
		emojiCounter[ec.Emoji] = ec.TotalCount
	}

	// Emojis are returned as an ordered list
	// as maps are randomly iterated
	for _, emoji := range emojis {
		var count = EmojiCount{emoji, emojiCounter[emoji]}
		emojiList = append(emojiList, count)
	}

	return emojiList, nil
}

func main() {
	mysqlHost := os.Getenv("DBHOST")
	cfg := mysql.Config{
		User:   os.Getenv("DBUSER"),
		Passwd: os.Getenv("DBPASS"),
		Net:    "tcp",
		Addr:   mysqlHost + ":3306",
		DBName: "emojis",
	}
	// Get a database handle.
	var err error
	db, err = sql.Open("mysql", cfg.FormatDSN())
	if err != nil {
		log.Fatal(err)
	}

	// Check db connection
	pingErr := db.Ping()
	if pingErr != nil {
		log.Fatal(pingErr)
	}
	fmt.Println("Connected!")

	r := gin.Default()
	r.LoadHTMLGlob("templates/*")

	// CORS configuration
	corsConfig := cors.DefaultConfig()
	corsConfig.AllowOrigins = []string{"*"}
	corsConfig.AllowHeaders = []string{"hx-current-url", "hx-request"}
	r.Use(cors.New(corsConfig))

	blogForm := r.Group("/blog/api/")
	{
		// Get the emoji form, you must provide postId query parameter
		blogForm.GET("/forms/emoji", func(c *gin.Context) {
			postId := c.Query("postId")

			// get emoji counts for each emoji
			emojiCounter, err := countEmojis(postId)
			if err != nil {
				c.HTML(http.StatusOK, "emoji_form.tmpl", gin.H{"error": "error getting the emoji counts", "postId": postId})
				return
			}

			// Return the html template
			c.HTML(http.StatusOK, "emoji_form.tmpl", gin.H{
				"postId":  c.Query("postId"),
				"results": emojiCounter,
			})
		})

		// Update the emoji counter, this handler will
		// add a new entry to the database with anonymized ip
		// then sums the results to get the emoji counter
		blogForm.POST("/forms/emoji/post", func(c *gin.Context) {
			postId := c.PostForm("postId")
			emoji := c.PostForm("emojiInput")

			// Check if parameters are missing
			if postId == "" || emoji == "" {
				c.HTML(http.StatusOK, "emoji_form.tmpl", gin.H{"error": "missing parameters", "postId": postId})
				return
			}

			// Add the new emoji entry to the database
			_, err := db.Exec("INSERT INTO emoji_clicks (post_id, emoji) VALUES (?, ?)", postId, emoji)
			if err != nil {
				c.HTML(http.StatusOK, "emoji_form.tmpl", gin.H{"error": "error writing to database", "postId": postId})
				return
			}

			// get emoji counts for each emoji
			emojiCounter, err := countEmojis(postId)
			if err != nil {
				c.HTML(http.StatusOK, "emoji_form.tmpl", gin.H{"error": "error getting the emoji counts", "postId": postId})
				return
			}

			// Return the html with the updated emoji counter
			c.HTML(http.StatusOK, "emoji_form.tmpl", gin.H{"postId": postId, "results": emojiCounter})
		})
	}

	r.Run(":8000")
}