[3단계 - 요금 정책 추가] 우르(김현우) 미션 제출합니다

src/main/java/subway/controller/LineController.java

@@ -2,12 +2,13 @@
 
 import org.springframework.http.HttpStatus;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.ResponseStatus;
 import org.springframework.web.bind.annotation.RestController;
-import subway.domain.Line;
+import subway.domain.line.Line;
 import subway.service.LineCommandService;
 import subway.service.LineQueryService;
 import subway.service.dto.LineResponse;
@@ -30,22 +31,29 @@ public LineController(final LineCommandService lineCommandService, final LineQue
 
     @GetMapping("/lines")
     @ResponseStatus(HttpStatus.OK)
-    public List<LineResponse> showLines(@RequestParam(value = "lineName", required = false) String lineName) {
+    public List<LineResponse> showLine(@RequestParam(value = "lineName", required = false) String lineName) {
         final List<Line> lines = lineQueryService.searchLines(lineName);
 
         return lines.stream()
-                    .map(line -> new LineResponse(line.getName(), mapToSectionResponseFrom(line)))
+                    .map(line -> new LineResponse(line.getName(), mapToSectionResponseFrom(line), line.getId()))
                     .collect(Collectors.toList());
     }
 
+    @GetMapping("/lines/{line-id}")
+    public LineResponse showLine(@PathVariable("line-id") Long lineId) {
+        final Line line = lineQueryService.searchByLineId(lineId);
+
+        return new LineResponse(line.getName(), mapToSectionResponseFrom(line), line.getId());
+    }
+
     @PostMapping("/lines")
     @ResponseStatus(HttpStatus.CREATED)
     public LineResponse registerLine(@RequestBody RegisterLineRequest registerLineRequest) {
         lineCommandService.registerLine(registerLineRequest);
 
         final Line line = lineQueryService.searchByLineName(registerLineRequest.getLineName());
 
-        return new LineResponse(line.getName(), mapToSectionResponseFrom(line));
+        return new LineResponse(line.getName(), mapToSectionResponseFrom(line), line.getId());
     }
 
     private List<SectionResponse> mapToSectionResponseFrom(final Line line) {

src/main/java/subway/controller/StationController.java

@@ -32,6 +32,7 @@ public StationRegisterResponse registerStation(@RequestBody StationRegisterReque
     }
 
     @DeleteMapping("/stations")
+    @ResponseStatus(HttpStatus.NO_CONTENT)
     public void deleteStation(@RequestBody StationDeleteRequest stationDeleteRequest) {
         stationService.deleteStation(stationDeleteRequest);
     }

src/main/java/subway/dao/LineDao.java

@@ -45,6 +45,16 @@ public List<LineEntity> findAll() {
         return jdbcTemplate.query(sql, rowMapper);
     }
 
+    public Optional<LineEntity> findByLineId(final Long lineId) {
+        final String sql = "SELECT * FROM LINE L WHERE L.id = ?";
+
+        try {
+            return Optional.ofNullable(jdbcTemplate.queryForObject(sql, rowMapper, lineId));
+        } catch (EmptyResultDataAccessException exception) {
+            return Optional.empty();
+        }
+    }
+
     public void deleteById(final Long lineId) {
         final String sql = "DELETE FROM LINE L WHERE L.id = ?";
 

src/main/java/subway/domain/Money.java

@@ -0,0 +1,66 @@
+package subway.domain;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.Objects;
+
+public class Money {
+
+    public static final Money ZERO = new Money(BigDecimal.ZERO);
+
+    private final BigDecimal value;
+
+    private Money(final BigDecimal value) {
+        validateNegative(value);
+        this.value = value;
+    }
+
+    public Money(final double value) {
+        this(BigDecimal.valueOf(value));
+    }
+
+    private void validateNegative(final BigDecimal value) {
+        if (value.doubleValue() < 0) {
+            throw new IllegalArgumentException("돈은 음수가 될 수 없습니다.");
+        }
+    }
+
+    public Money minus(final int value) {
+        return new Money(this.value.subtract(BigDecimal.valueOf(value)));
+    }
+
+    public Money calculateDiscountedPrice(final int percentage) {
+        final int discountedPercentage = 100 - percentage;
+        return new Money(this.value.multiply(BigDecimal.valueOf(discountedPercentage))
+                                   .divide(BigDecimal.valueOf(100), RoundingMode.HALF_DOWN));
+    }
+
+    public Money add(final BigDecimal value) {
+        return new Money(this.value.add(value));
+    }
+
+    public Money add(final Money money) {
+        return new Money(this.value.add(money.value));
+    }
+
+    public Money max(final Money other) {
+        return new Money(this.value.max(other.value));
+    }
+
+    public double getValue() {
+        return value.doubleValue();
+    }
+
+    @Override
+    public boolean equals(final Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        final Money money = (Money) o;
+        return Objects.equals(value, money.value);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(value);
+    }
+}

src/main/java/subway/domain/Line.java → src/main/java/subway/domain/line/Line.java

@@ -1,4 +1,7 @@
-package subway.domain;
+package subway.domain.line;
+
+import subway.domain.section.Section;
+import subway.domain.station.Station;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -54,12 +57,23 @@ public void add(Section newSection) {
         }
 
         final Section targetSection = starter.findPreSectionOnAdd(newSection);
+        final Section sameStartSection = starter.findSameSectionOnAdd(newSection);
 
         if (canExchangeStarter(targetSection)) {
+
             if (starter.isLinked(newSection)) {
                 exchangeStarterOnAdd(newSection);
                 return;
             }
+
+            if (sameStartSection != null) {
+                newSection.updateNextSection(starter);
+                starter.updateSectionOnAdd(newSection);
+                starter = newSection;
+                return;
+            }
+
+
             throw new IllegalArgumentException("해당 섹션은 현재 Line에 추가할 수 없습니다.");
         }
 

src/main/java/subway/domain/policy/ChargePolicyComposite.java

@@ -0,0 +1,42 @@
+package subway.domain.policy;
+
+import org.springframework.context.annotation.Primary;
+import org.springframework.stereotype.Component;
+import subway.domain.Money;
+import subway.domain.policy.discount.DiscountCondition;
+import subway.domain.policy.discount.SubwayDiscountPolicy;
+import subway.domain.policy.fare.SubwayFarePolicy;
+import subway.domain.route.Route;
+
+import java.util.List;
+
+@Primary
+@Component
+public class ChargePolicyComposite implements SubwayFarePolicy, SubwayDiscountPolicy {
+
+    private final List<SubwayFarePolicy> farePolicies;
+    private final List<SubwayDiscountPolicy> discountPolicies;
+
+    public ChargePolicyComposite(
+            final List<SubwayFarePolicy> farePolicies,
+            final List<SubwayDiscountPolicy> discountPolicies
+    ) {
+        this.farePolicies = farePolicies;
+        this.discountPolicies = discountPolicies;
+    }
+
+    @Override
+    public Money calculate(final Route route) {
+        return farePolicies.stream()
+                           .map(it -> it.calculate(route))
+                           .reduce(Money.ZERO, Money::add);
+    }
+
+    @Override
+    public Money discount(final DiscountCondition discountCondition, final Money price) {
+        return discountPolicies.stream()
+                               .reduce(price, (money, subwayDiscountPolicy) ->
+                                               subwayDiscountPolicy.discount(discountCondition, money),
+                                       (money1, money2) -> money2);
+    }
+}

src/main/java/subway/domain/policy/discount/AgeDiscountPolicy.java

@@ -0,0 +1,48 @@
+package subway.domain.policy.discount;
+
+import org.springframework.stereotype.Component;
+import subway.domain.Money;
+
+import java.util.EnumMap;
+import java.util.Map;
+
+@Component
+public class AgeDiscountPolicy implements SubwayDiscountPolicy {
+
+    private static final Map<AgeGroup, DiscountValue> policyMap = new EnumMap<>(AgeGroup.class);
+
+    static {
+        policyMap.put(AgeGroup.CHILD, new DiscountValue(350, 50));
+        policyMap.put(AgeGroup.TEENAGER, new DiscountValue(350, 20));
+        policyMap.put(AgeGroup.NONE, new DiscountValue(0, 0));
+    }
+
+    @Override
+    public Money discount(final DiscountCondition discountCondition, final Money price) {
+
+        final AgeGroup ageGroup = AgeGroup.findAgeGroup(discountCondition.getAge());
+        final DiscountValue discountValue = policyMap.get(ageGroup);
+
+        return price.minus(discountValue.getDiscountPrice())
+                    .calculateDiscountedPrice(discountValue.getPercent());
+    }
+
+    private static class DiscountValue {
+
+        private final int discountPrice;
+        private final int percent;
+
+        public DiscountValue(final int discountPrice, final int percent) {
+            this.discountPrice = discountPrice;
+            this.percent = percent;
+        }
+
+        public int getDiscountPrice() {
+            return discountPrice;
+        }
+
+        public int getPercent() {
+            return percent;
+        }
+    }
+}

src/main/java/subway/domain/policy/discount/AgeGroup.java

@@ -0,0 +1,27 @@
+package subway.domain.policy.discount;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+public enum AgeGroup {
+
+    TEENAGER(13, 19),
+    CHILD(6, 13),
+    NONE(0, 0);
+
+    private final int ageLowLimit;
+    private final int ageHighLimit;
+
+    AgeGroup(final int ageLowLimit, final int ageHighLimit) {
+        this.ageLowLimit = ageLowLimit;
+        this.ageHighLimit = ageHighLimit;
+    }
+
+    public static AgeGroup findAgeGroup(final Integer target) {
+        return Arrays.stream(values())
+                     .filter(age -> Objects.nonNull(target))
+                     .filter(age -> target >= age.ageLowLimit && target < age.ageHighLimit)
+                     .findAny()
+                     .orElse(NONE);
+    }
+}

src/main/java/subway/domain/policy/discount/DiscountCondition.java

@@ -0,0 +1,14 @@
+package subway.domain.policy.discount;
+
+public class DiscountCondition {
+
+    private final Integer age;
+
+    public DiscountCondition(final Integer age) {
+        this.age = age;
+    }
+
+    public Integer getAge() {
+        return age;
+    }
+}

src/main/java/subway/domain/policy/discount/SubwayDiscountPolicy.java

@@ -0,0 +1,8 @@
+package subway.domain.policy.discount;
+
+import subway.domain.Money;
+
+public interface SubwayDiscountPolicy {
+
+    Money discount(final DiscountCondition discountCondition, final Money price);
+}