Implement getElectionResults

cmd/web/handlers.go

@@ -9,6 +9,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"math"
 	"math/rand"
 	"net/http"
 	"slices"
@@ -271,5 +272,41 @@ func (app *application) createVotesHandleUnknownVotersElection(w http.ResponseWr
 }
 
 func (app *application) GetElectionResults(w http.ResponseWriter, r *http.Request, id int) {
+	votes, err := app.votes.GetByElection(id)
+	if err != nil {
+		if errors.Is(sql.ErrNoRows, err) {
+			app.clientError(w, http.StatusNotFound, fmt.Sprintf("couldn't find votes for an election with id %v", id))
+			return
+		}
+		app.serverError(w, r, err)
+		return
+	}
 
+	results := getResultsFromVotes(votes)
+
+	response, err := json.Marshal(api.ElectionResultsResponse{Results: &results})
+	if err != nil {
+		app.serverError(w, r, err)
+		return
+	}
+
+	w.Write(response)
+}
+
+func getResultsFromVotes(votes *[]models.Vote) []api.VotesForChoice {
+	votesForChoice := make(map[string]int)
+	for _, v := range *votes {
+		votesForChoice[v.ChoiceText] += int(math.Floor(math.Sqrt(float64(v.Tokens))))
+	}
+
+	results := make([]api.VotesForChoice, 0)
+	for choice, votes := range votesForChoice {
+		result := api.VotesForChoice{
+			Choice: choice,
+			Votes:  votes,
+		}
+		results = append(results, result)
+	}
+
+	return results
 }

cmd/web/openapi.yml

@@ -124,6 +124,12 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/ElectionResultsResponse"
+        400:
+          description: Request malformed
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/ErrorResponse"
         404:
           description: Election doesn't exist
           content:
@@ -205,6 +211,22 @@ components:
 
     ElectionResultsResponse:
       type: object
+      properties:
+        results:
+          type: array
+          items:
+            $ref: "#/components/schemas/VotesForChoice"
+
+    VotesForChoice:
+      type: object
+      required:
+        - choice
+        - votes
+      properties:
+        choice:
+          type: string
+        votes:
+          type: integer
 
     ErrorResponse:
       type: object

internal/generated.go

@@ -42,7 +42,9 @@ type CreateVotesRequest struct {
 }
 
 // ElectionResultsResponse defines model for ElectionResultsResponse.
-type ElectionResultsResponse = map[string]interface{}
+type ElectionResultsResponse struct {
+	Results *[]VotesForChoice `json:"results,omitempty"`
+}
 
 // ErrorResponse defines model for ErrorResponse.
 type ErrorResponse struct {
@@ -56,6 +58,12 @@ type ErrorResponse struct {
 	Message string `json:"message"`
 }
 
+// VotesForChoice defines model for VotesForChoice.
+type VotesForChoice struct {
+	Choice string `json:"choice"`
+	Votes  int    `json:"votes"`
+}
+
 // CreateElectionJSONRequestBody defines body for CreateElection for application/json ContentType.
 type CreateElectionJSONRequestBody = CreateElectionRequest
 

internal/models/votes.go

@@ -3,17 +3,27 @@ package models
 import (
 	"database/sql"
 	"errors"
+	"time"
 )
 
 type VoteModelInterface interface {
 	Insert(voterIdentity string, electionId int, choiceText string, tokens int) (int, error)
 	Exists(voterIdentity string, electionID int) (bool, error)
+	GetByElection(electionID int) (*[]Vote, error)
 }
 
 type VoteModel struct {
 	DB *sql.DB
 }
 
+type Vote struct {
+	VoterIdentity string
+	ElectionID    int
+	ChoiceText    string
+	Tokens        int
+	CreatedAt     time.Time
+}
+
 func (v *VoteModel) Insert(voterIdentity string, electionId int, choiceText string, tokens int) (int, error) {
 	tx, err := v.DB.Begin()
 	if err != nil {
@@ -55,3 +65,43 @@ func (v *VoteModel) Exists(voterIdentity string, electionID int) (bool, error) {
 	}
 	return exists, nil
 }
+
+func (v *VoteModel) GetByElection(electionID int) (*[]Vote, error) {
+	query := `
+		SELECT voter_identity, election_id, choice_text, tokens, created_at
+		FROM votes
+		WHERE election_id = ?
+	`
+
+	rows, err := v.DB.Query(query, electionID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var votes []Vote
+	for rows.Next() {
+		var vote Vote
+		err := rows.Scan(
+			&vote.VoterIdentity,
+			&vote.ElectionID,
+			&vote.ChoiceText,
+			&vote.Tokens,
+			&vote.CreatedAt,
+		)
+		if err != nil {
+			return nil, err
+		}
+		votes = append(votes, vote)
+	}
+
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+
+	if len(votes) == 0 {
+		return nil, sql.ErrNoRows
+	}
+
+	return &votes, nil
+}