package main

import (
	"net/http"

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

// album represents data about a record album.
type album struct {
	ID     string `json:"id"`
	Title  string `json:"title"`
	Artist string `json:"artist"`
	Price  string `json:"price"`
}

// albums slice to seed record album data.
var albums = []album{
	{ID: "1", Title: "Blue Train", Artist: "John Coltrane", Price: "56.99"},
	{ID: "2", Title: "Jeru", Artist: "Gerry Mulligan", Price: "17.99"},
	{ID: "3", Title: "Sarah Vaughan and Clifford Brown", Artist: "Sarah Vaughan", Price: "39.99"},
}

func remove(slice []album, s int) []album {
	return append(slice[:s], slice[s+1:]...)
}

func main() {
	router := gin.Default()
	router.GET("/albums", getAlbums)
	router.GET("/albums/:id", getAlbumByID)
	router.POST("/albums", postAlbums)
	router.DELETE("/albums", delAlbums)
	router.DELETE("/albums/:id", delAlbumByID)
	router.PATCH("/albums/:id", updateAlbum)

	router.Run("localhost:8080")
}

// getAlbums responds with the list of all albums as JSON.
func getAlbums(c *gin.Context) {
	c.IndentedJSON(http.StatusOK, albums)
}

// postAlbums adds an album from JSON received in the request body.
func postAlbums(c *gin.Context) {
	var newAlbum album

	// Call BindJSON to bind the received JSON to
	// newAlbum.
	if err := c.BindJSON(&newAlbum); err != nil {
		return
	}

	// Add the new album to the slice.
	albums = append(albums, newAlbum)
	c.IndentedJSON(http.StatusCreated, newAlbum)
}

// getAlbumByID locates the album whose ID value matches the id
// parameter sent by the client, then returns that album as a response.
func getAlbumByID(c *gin.Context) {
	id := c.Param("id")

	// Loop through the list of albums, looking for
	// an album whose ID value matches the parameter.
	for _, a := range albums {
		if a.ID == id {
			c.IndentedJSON(http.StatusOK, a)
			return
		}
	}
	c.IndentedJSON(http.StatusNotFound, gin.H{"message": "album not found"})
}

func delAlbums(c *gin.Context) {
	albums = []album{}
	c.IndentedJSON(http.StatusOK, albums)
}

func delAlbumByID(c *gin.Context) {
	id := c.Param("id")

	for s, a := range albums {
		if a.ID == id {
			albums = remove(albums, s)
			c.IndentedJSON(http.StatusOK, albums)
			return
		}
	}
	c.IndentedJSON(http.StatusNotFound, gin.H{"message": "album not found"})
}

func updateAlbum(c *gin.Context) {
	id := c.Param("id")

	var newAlbum album

	if err := c.BindJSON(&newAlbum); err != nil {
		return
	}

	for s, a := range albums {
		if a.ID == id {
			albums = remove(albums, s)
			albums = append(albums, newAlbum)
			c.IndentedJSON(http.StatusOK, newAlbum)
			return
		}
	}
	c.IndentedJSON(http.StatusNotFound, gin.H{"message": "album not found"})
}