Dirty implementation of createVotes

cmd/web/handlers.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"math/rand"
 	"net/http"
+	"slices"
 	"time"
 )
 
@@ -140,22 +141,95 @@ func (app *application) createVotes(w http.ResponseWriter, r *http.Request) {
 		app.serverError(w, r, err)
 	}
 
-	// TODO check if he has voted
-
-	//var voterIdentity string
-	if election.AreVotersKnown {
-		if request.VoterIdentity == nil || validator.Blank(*request.VoterIdentity) {
-			app.unprocessableEntityErrorSingle(w, fmt.Errorf("election has known voters; you must provide an identity provided by the organizer"))
+	for _, c := range request.Choices {
+		choiceExists := slices.Contains(election.Choices, c.ChoiceText)
+		if !choiceExists {
+			app.unprocessableEntityErrorSingle(w, fmt.Errorf("choice %v doesn't exist", c.ChoiceText))
 			return
 		}
-		//voterIdentity = *request.VoterIdentity
-	} else {
-		// TODO: get requester's IP address as identity
 	}
 
-	// TODO verify if choice exists
-	// TODO count tokens to make sure user isn't trying to cheat
+	tokensUsed := 0
+	for _, c := range request.Choices {
+		tokensUsed += c.Tokens
+	}
 
-	json, _ := json.Marshal(election)
-	w.Write(json)
+	if tokensUsed > election.Tokens {
+		app.unprocessableEntityErrorSingle(w, fmt.Errorf("you used too many tokens; must not exceed %v tokens", election.Tokens))
+		return
+	}
+
+	electionHasExpired := election.ExpiresAt.Before(time.Now())
+	if electionHasExpired {
+		app.unprocessableEntityErrorSingle(w, fmt.Errorf("election has expired"))
+		return
+	}
+
+	// this snippet of code also inserts in the `voters` table
+	voterIdentity := func() string {
+		var voterIdentity string
+		if election.AreVotersKnown {
+			if request.VoterIdentity == nil || validator.Blank(*request.VoterIdentity) {
+				app.unprocessableEntityErrorSingle(w, fmt.Errorf("election has known voters; you must provide an identity provided by the organizer"))
+				return ""
+			}
+
+			voterIdentity = *request.VoterIdentity
+			hasCastVotes, err := app.votes.Exists(voterIdentity, election.ID)
+			if err != nil {
+				app.serverError(w, r, err)
+				return ""
+			}
+			if hasCastVotes {
+				app.unprocessableEntityErrorSingle(w, fmt.Errorf("you already voted"))
+				return ""
+			}
+		} else {
+			voterIdentity = r.RemoteAddr
+
+			// if voters are known, voter will always exist
+			voterExists, err := app.voters.Exists(voterIdentity, election.ID)
+			if err != nil {
+				app.serverError(w, r, err)
+				return ""
+			}
+			if voterExists {
+				app.unprocessableEntityErrorSingle(w, fmt.Errorf("you already voted"))
+				return ""
+			}
+
+			_, err = app.voters.Insert(voterIdentity, election.ID)
+			if err != nil {
+				app.serverError(w, r, err)
+				return ""
+			}
+		}
+		return voterIdentity
+	}()
+
+	if voterIdentity == "" {
+		return
+	}
+
+	if !election.AreVotersKnown {
+		voterCount, err := app.voters.CountByElection(election.ID)
+		if err != nil && !errors.Is(sql.ErrNoRows, err) {
+			app.serverError(w, r, err)
+			return
+		}
+		// if voters are known, voterCount == election.MaxVoters in all cases
+		if voterCount == election.MaxVoters {
+			app.unprocessableEntityErrorSingle(w, fmt.Errorf("maximum voters reached"))
+			return
+		}
+	}
+
+	for _, c := range request.Choices {
+		_, err := app.votes.Insert(voterIdentity, election.ID, c.ChoiceText, c.Tokens)
+		if err != nil {
+			app.serverError(w, r, err)
+		}
+	}
+
+	w.WriteHeader(http.StatusCreated)
 }

cmd/web/main.go

@@ -39,6 +39,7 @@ func main() {
 		logger:    logger,
 		elections: &models.ElectionModel{DB: db},
 		voters:    &models.VoterModel{DB: db},
+		votes:     &models.VoteModel{DB: db},
 	}
 
 	logger.Info("Starting server", "addr", addr)

cmd/web/routes.go

@@ -11,6 +11,7 @@ type application struct {
 	logger    *slog.Logger
 	elections models.ElectionModelInterface
 	voters    models.VoterModelInterface
+	votes     models.VoteModelInterface
 }
 
 func (app *application) routes() http.Handler {

cmd/web/testutils_test.go

@@ -15,6 +15,7 @@ func newTestApplication(t *testing.T) *application {
 		logger:    slog.New(slog.NewTextHandler(io.Discard, nil)),
 		elections: &mockElectionModel{},
 		voters:    &mockVoterModel{},
+		votes:     &mockVoteModel{},
 	}
 }
 
@@ -56,8 +57,8 @@ func (e *mockElectionModel) GetById(id int) (*models.Election, error) {
 		Tokens:         100,
 		AreVotersKnown: false,
 		MaxVoters:      10,
-		CreatedAt:      time.Now().String(),
-		ExpiresAt:      time.Now().Add(100 * time.Hour).String(),
+		CreatedAt:      time.Now(),
+		ExpiresAt:      time.Now().Add(100 * time.Hour),
 	}, nil
 }
 
@@ -67,3 +68,22 @@ type mockVoterModel struct {
 func (v *mockVoterModel) Insert(identity string, electionID int) (int, error) {
 	return 1, nil
 }
+
+func (v *mockVoterModel) CountByElection(electionID int) (int, error) {
+	return 10, nil
+}
+
+func (v *mockVoterModel) Exists(voterIdentity string, electionID int) (bool, error) {
+	return true, nil
+}
+
+type mockVoteModel struct {
+}
+
+func (v *mockVoteModel) Insert(voterIdentity string, electionId int, choiceText string, tokens int) (int, error) {
+	return 1, nil
+}
+
+func (v *mockVoteModel) Exists(voterIdentity string, electionID int) (bool, error) {
+	return true, nil
+}

internal/models/elections.go

@@ -20,8 +20,8 @@ type Election struct {
 	Tokens         int
 	AreVotersKnown bool
 	MaxVoters      int
-	CreatedAt      string
-	ExpiresAt      string
+	CreatedAt      time.Time
+	ExpiresAt      time.Time
 	Choices        []string
 }
 

internal/models/voters.go

@@ -2,10 +2,13 @@ package models
 
 import (
 	"database/sql"
+	"errors"
 )
 
 type VoterModelInterface interface {
 	Insert(identity string, electionID int) (int, error)
+	CountByElection(electionID int) (int, error)
+	Exists(voterIdentity string, electionID int) (bool, error)
 }
 
 type VoterModel struct {
@@ -34,3 +37,53 @@ func (v *VoterModel) Insert(identity string, electionID int) (int, error) {
 	voterId, err := result.LastInsertId()
 	return int(voterId), nil
 }
+
+func (v *VoterModel) CountByElection(electionID int) (int, error) {
+	// use a transaction to prevent race conditions
+	tx, err := v.DB.Begin()
+	if err != nil {
+		return 0, err
+	}
+	defer tx.Rollback()
+
+	query := `
+		SELECT COUNT(identity)
+		FROM voters
+		WHERE election_id = ?
+		GROUP BY election_id;
+	`
+
+	row := tx.QueryRow(query, electionID)
+
+	var voterCount int
+
+	err = row.Scan(&voterCount)
+	if err != nil {
+		return 0, err
+	}
+
+	tx.Commit()
+
+	return voterCount, nil
+}
+
+func (v *VoterModel) Exists(voterIdentity string, electionID int) (bool, error) {
+	query := `
+		SELECT EXISTS (
+			SELECT 1
+			FROM voters
+			WHERE identity = ? AND election_id = ?
+		)
+	`
+
+	var exists bool
+
+	err := v.DB.QueryRow(query, voterIdentity, electionID).Scan(&exists)
+	if err != nil {
+		if errors.Is(sql.ErrNoRows, err) {
+			return false, nil
+		}
+		return false, err
+	}
+	return exists, nil
+}

internal/models/votes.go

@@ -0,0 +1,57 @@
+package models
+
+import (
+	"database/sql"
+	"errors"
+)
+
+type VoteModelInterface interface {
+	Insert(voterIdentity string, electionId int, choiceText string, tokens int) (int, error)
+	Exists(voterIdentity string, electionID int) (bool, error)
+}
+
+type VoteModel struct {
+	DB *sql.DB
+}
+
+func (v *VoteModel) Insert(voterIdentity string, electionId int, choiceText string, tokens int) (int, error) {
+	tx, err := v.DB.Begin()
+	if err != nil {
+		return 0, err
+	}
+	defer tx.Rollback()
+
+	result, err := tx.Exec(`
+        INSERT INTO votes (voter_identity, election_id, choice_text, tokens)
+        VALUES (?, ?, ?, ?)`,
+		voterIdentity, electionId, choiceText, tokens)
+	if err != nil {
+		return 0, err
+	}
+
+	if err = tx.Commit(); err != nil {
+		return 0, err
+	}
+
+	voteId, err := result.LastInsertId()
+	return int(voteId), nil
+}
+
+func (v *VoteModel) Exists(voterIdentity string, electionID int) (bool, error) {
+	var exists bool
+	query := `
+		SELECT EXISTS (
+			SELECT 1
+			FROM votes
+			WHERE voter_identity = ? AND election_id = ?
+		)
+	`
+	err := v.DB.QueryRow(query, voterIdentity, electionID).Scan(&exists)
+	if err != nil {
+		if errors.Is(sql.ErrNoRows, err) {
+			return false, nil
+		}
+		return false, err
+	}
+	return exists, nil
+}