Levyraati26_go/reviews.go

package main

import (
	"context"
	"errors"
	"fmt"
	"log/slog"
	"net/http"
	"strconv"
	"time"

	"github.com/jackc/pgx/v5"
)

const (
	editWindow = 30 * time.Minute
	maxReview  = 5000
)

type review struct {
	ID         int64
	SongID     int64
	ReviewerID int64
	Reviewer   string
	Score      int
	Text       string
	CreatedAt  time.Time
	UpdatedAt  time.Time
	Own        bool
}

// The window is measured from updated_at, so an edit extends it. It gates deletion as well as
// editing: for 30 minutes a review is yours to change or withdraw, after that it is on the record.
func (r *review) EditableUntil() time.Time { return r.UpdatedAt.Add(editWindow) }
func (r *review) CanEdit() bool            { return r.Own && time.Now().Before(r.EditableUntil()) }

func (r *review) Initials() string {
	m := member{Name: r.Reviewer}
	return m.Initials()
}

func (a *app) reviewsFor(ctx context.Context, songID, viewerID int64) ([]*review, error) {
	rows, err := a.pool.Query(ctx, `
		select r.id, r.song_id, r.reviewer_id, u.name, r.score, r.text, r.created_at, r.updated_at,
		       r.reviewer_id = $2
		  from reviews r join users u on u.id = r.reviewer_id
		 where r.song_id = $1
		 order by r.created_at`, songID, viewerID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []*review
	for rows.Next() {
		var v review
		if err := rows.Scan(&v.ID, &v.SongID, &v.ReviewerID, &v.Reviewer, &v.Score, &v.Text,
			&v.CreatedAt, &v.UpdatedAt, &v.Own); err != nil {
			return nil, err
		}
		out = append(out, &v)
	}
	return out, rows.Err()
}

func (a *app) viewerReview(ctx context.Context, songID, viewerID int64) (*review, error) {
	var v review
	err := a.pool.QueryRow(ctx, `
		select r.id, r.song_id, r.reviewer_id, u.name, r.score, r.text, r.created_at, r.updated_at, true
		  from reviews r join users u on u.id = r.reviewer_id
		 where r.song_id = $1 and r.reviewer_id = $2`, songID, viewerID).
		Scan(&v.ID, &v.SongID, &v.ReviewerID, &v.Reviewer, &v.Score, &v.Text,
			&v.CreatedAt, &v.UpdatedAt, &v.Own)
	if errors.Is(err, pgx.ErrNoRows) {
		return nil, nil
	}
	return &v, err
}

func reviewInput(r *http.Request) (int, string, string) {
	score, _ := strconv.Atoi(r.FormValue("score"))
	text := clean(r.FormValue("text"), maxReview)
	switch {
	case score < 1 || score > 100:
		return 0, "", "Pisteiden tulee olla 1–100."
	case text == "":
		return 0, "", "Kirjoita muutama sana."
	}
	return score, text, ""
}

func (a *app) createReview(w http.ResponseWriter, r *http.Request) {
	songID, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	me := memberFrom(r.Context())
	score, text, problem := reviewInput(r)
	if problem != "" {
		a.flash(w, problem)
		http.Redirect(w, r, fmt.Sprintf("/songs/%d", songID), http.StatusSeeOther)
		return
	}

	// You cannot review your own song, and the unique constraint is what stops a second review —
	// no read-then-write race to lose.
	var submitter int64
	err = a.pool.QueryRow(r.Context(), `select submitted_by from songs where id = $1`, songID).Scan(&submitter)
	if errors.Is(err, pgx.ErrNoRows) {
		http.NotFound(w, r)
		return
	} else if err != nil {
		slog.Error("load song", "ctx", "reviews", "error", err, "song", songID)
		http.Error(w, "virhe", http.StatusInternalServerError)
		return
	}
	if submitter == me.ID {
		http.Error(w, "omaa kappaletta ei voi arvostella", http.StatusForbidden)
		return
	}

	_, err = a.pool.Exec(r.Context(),
		`insert into reviews (song_id, reviewer_id, score, text) values ($1, $2, $3, $4)`,
		songID, me.ID, score, text)
	if isUnique(err) {
		a.flash(w, "Olet jo arvostellut tämän kappaleen.")
		http.Redirect(w, r, fmt.Sprintf("/songs/%d", songID), http.StatusSeeOther)
		return
	} else if err != nil {
		slog.Error("create review", "ctx", "reviews", "error", err, "song", songID)
		http.Error(w, "virhe", http.StatusInternalServerError)
		return
	}

	slog.Info("review written", "ctx", "reviews", "song", songID, "user", me.ID)
	a.flash(w, "Arvostelu tallennettu. Nyt näet muidenkin arvostelut.")
	http.Redirect(w, r, fmt.Sprintf("/songs/%d", songID), http.StatusSeeOther)
}

// Both edit and delete are gated by the same window, in the same WHERE clause — the database
// decides, so there is no clock-check in Go to get subtly wrong.
func (a *app) editReview(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	score, text, problem := reviewInput(r)
	if problem != "" {
		a.flash(w, problem)
		http.Redirect(w, r, r.FormValue("from"), http.StatusSeeOther)
		return
	}

	var songID int64
	err = a.pool.QueryRow(r.Context(), `
		update reviews set score = $3, text = $4, updated_at = now()
		 where id = $1 and reviewer_id = $2 and updated_at > now() - $5::interval
		 returning song_id`,
		id, memberFrom(r.Context()).ID, score, text, editWindow.String()).Scan(&songID)
	if errors.Is(err, pgx.ErrNoRows) {
		a.flash(w, "Muokkausaika on umpeutunut.")
		http.Redirect(w, r, r.FormValue("from"), http.StatusSeeOther)
		return
	} else if err != nil {
		slog.Error("edit review", "ctx", "reviews", "error", err, "review", id)
		http.Error(w, "virhe", http.StatusInternalServerError)
		return
	}
	a.flash(w, "Arvostelu päivitetty.")
	http.Redirect(w, r, fmt.Sprintf("/songs/%d", songID), http.StatusSeeOther)
}

// Deleting the last review unlocks the song for its submitter again — locked is a live state, and
// the 30-minute window is what keeps that from being a rug-pull months later.
func (a *app) deleteReview(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	var songID int64
	err = a.pool.QueryRow(r.Context(), `
		delete from reviews
		 where id = $1 and reviewer_id = $2 and updated_at > now() - $3::interval
		 returning song_id`,
		id, memberFrom(r.Context()).ID, editWindow.String()).Scan(&songID)
	if errors.Is(err, pgx.ErrNoRows) {
		a.flash(w, "Muokkausaika on umpeutunut.")
		http.Redirect(w, r, r.FormValue("from"), http.StatusSeeOther)
		return
	} else if err != nil {
		slog.Error("delete review", "ctx", "reviews", "error", err, "review", id)
		http.Error(w, "virhe", http.StatusInternalServerError)
		return
	}
	slog.Info("review deleted", "ctx", "reviews", "review", id, "song", songID)
	a.flash(w, "Arvostelu poistettu.")
	http.Redirect(w, r, fmt.Sprintf("/songs/%d", songID), http.StatusSeeOther)
}