Add team create and retrieve functionalities

src/main/java/com/luka/levi9/controller/TeamController.java

@@ -0,0 +1,33 @@
+package com.luka.levi9.controller;
+
+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.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import com.luka.levi9.dto.TeamCreationRequest;
+import com.luka.levi9.model.Team;
+import com.luka.levi9.service.TeamService;
+
+import lombok.AllArgsConstructor;
+
+@RestController
+@AllArgsConstructor
+@RequestMapping("/teams")
+public class TeamController {
+
+	private final TeamService teamService;
+
+	@PostMapping()
+	public Team createTeam(@RequestBody TeamCreationRequest request) {
+		return teamService.createTeam(request);
+	}
+
+	@GetMapping("/{id}")
+	public Team getTeam(@PathVariable String id) {
+		return teamService.getTeam(id);
+	}
+
+}

src/main/java/com/luka/levi9/dto/TeamCreationRequest.java

@@ -0,0 +1,16 @@
+package com.luka.levi9.dto;
+
+import java.util.List;
+
+import com.fasterxml.jackson.annotation.JsonAlias;
+
+import lombok.Getter;
+import lombok.Setter;
+
+@Getter
+@Setter
+public class TeamCreationRequest {
+	private String teamName;
+	@JsonAlias("players")
+	private List<String> playerIds;
+}

src/main/java/com/luka/levi9/exception/PlayerNotFoundException.java → src/main/java/com/luka/levi9/exception/NotFoundException.java

@@ -4,11 +4,11 @@
 import org.springframework.web.bind.annotation.ResponseStatus;
 
 @ResponseStatus(HttpStatus.NOT_FOUND)
-public class PlayerNotFoundException extends RuntimeException {
+public class NotFoundException extends RuntimeException {
 
 	private static final long serialVersionUID = -1616826993751458020L;
 
-	public PlayerNotFoundException(String message) {
+	public NotFoundException(String message) {
 		super(message);
 	}
 

src/main/java/com/luka/levi9/exception/TeamValidationException.java

@@ -0,0 +1,13 @@
+package com.luka.levi9.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+import lombok.experimental.StandardException;
+
+@StandardException
+@ResponseStatus(HttpStatus.BAD_REQUEST)
+public class TeamValidationException extends RuntimeException {
+
+	private static final long serialVersionUID = -7317190995382988861L;
+}

src/main/java/com/luka/levi9/repository/TeamRepository.java

@@ -0,0 +1,12 @@
+package com.luka.levi9.repository;
+
+import java.util.Optional;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import com.luka.levi9.model.Team;
+
+public interface TeamRepository extends JpaRepository<Team, String> {
+
+	Optional<Team> findByTeamName(String teamName);
+}

src/main/java/com/luka/levi9/service/PlayerService.java

@@ -3,19 +3,18 @@
 import org.springframework.stereotype.Service;
 
 import com.luka.levi9.exception.PlayerAlreadyExistsException;
-import com.luka.levi9.exception.PlayerNotFoundException;
+import com.luka.levi9.exception.NotFoundException;
 import com.luka.levi9.model.Player;
 import com.luka.levi9.repository.PlayerRepository;
 
+import lombok.AllArgsConstructor;
+
 @Service
+@AllArgsConstructor
 public class PlayerService {
 
 	private final PlayerRepository playerRepository;
 
-	public PlayerService(PlayerRepository playerRepository) {
-		this.playerRepository = playerRepository;
-	}
-
 	public Player createPlayer(Player player) {
 		if (playerRepository.findByNickname(player.getNickname()).isPresent())
 			throw new PlayerAlreadyExistsException("Player with nickname " + player.getNickname() + " already exists.");
@@ -25,6 +24,6 @@ public Player createPlayer(Player player) {
 
 	public Player getPlayer(String id) {
 		return playerRepository.findById(id)
-				.orElseThrow(() -> new PlayerNotFoundException("Player with id " + id + " not found."));
+				.orElseThrow(() -> new NotFoundException("Player with id " + id + " not found."));
 	}
 }

src/main/java/com/luka/levi9/service/TeamService.java

@@ -0,0 +1,65 @@
+package com.luka.levi9.service;
+
+import java.util.List;
+
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import com.luka.levi9.dto.TeamCreationRequest;
+import com.luka.levi9.exception.NotFoundException;
+import com.luka.levi9.exception.TeamValidationException;
+import com.luka.levi9.model.Player;
+import com.luka.levi9.model.Team;
+import com.luka.levi9.repository.PlayerRepository;
+import com.luka.levi9.repository.TeamRepository;
+
+import lombok.AllArgsConstructor;
+
+@Service
+@AllArgsConstructor
+public class TeamService {
+
+	private final TeamRepository teamRepository;
+	private final PlayerRepository playerRepository;
+
+	@Transactional
+	public Team createTeam(TeamCreationRequest teamDto) {
+		if (teamRepository.findByTeamName(teamDto.getTeamName()).isPresent())
+			throw new TeamValidationException("Team with name " + teamDto.getTeamName() + " already exists.");
+
+		List<Player> players = playerRepository.findAllById(teamDto.getPlayerIds());
+
+		validatePlayers(teamDto, players);
+
+		return saveTeam(teamDto, players);
+	}
+
+	private void validatePlayers(TeamCreationRequest teamDto, List<Player> players) {
+		if (players.size() != teamDto.getPlayerIds().size())
+			throw new TeamValidationException("Some players were not found.");
+
+		if (players.size() != 5)
+			throw new TeamValidationException("A team must have exactly 5 players.");
+
+		players.stream().filter(player -> player.getTeam() != null).findAny().ifPresent(player -> {
+			throw new TeamValidationException(
+					"Player with ID " + player.getId() + " is already in a team and cannot join another.");
+		});
+	}
+
+	private Team saveTeam(TeamCreationRequest teamDto, List<Player> players) {
+		Team newTeam = new Team();
+		newTeam.setTeamName(teamDto.getTeamName());
+		newTeam.setPlayers(players);
+
+		players.forEach(player -> player.setTeam(newTeam));
+
+		return teamRepository.save(newTeam);
+	}
+
+	public Team getTeam(String id) {
+		return teamRepository.findById(id)
+				.orElseThrow(() -> new NotFoundException("Team with id " + id + " not found."));
+	}
+
+}