add 'map' cli command to provide map information (#100)

* add 'map' cli command

- provides the following map information functions:
  - list all available maps in the global registry
  - display map metadata

- update docs with map command examples

* add list and info subcommands to map cli command

* rename map command list and info factory functions

* add --all flag to map info subcommand

* handle cmd.Help error

cli/README.md

@@ -78,6 +78,25 @@ Example creating a 7x7 Standard game with two Battlesnakes:
 battlesnake play --width 7 --height 7 --name Snake1 --url http://snake1-url-whatever --name Snake2 --url http://snake2-url-whatever
 ```
 
+### Maps
+The `map` command provides map information for use with the `play` command.
+
+List all available maps using the `list` subcommand:
+```
+battlesnake map list
+```
+Display map information using the `info` subcommand:
+```
+battlesnake map info standard
+Name: Standard
+Author: Battlesnake
+Description: Standard snake placement and food spawning
+Version: 2
+Min Players: 1
+Max Players: 16
+Board Sizes (WxH): 7x7 9x9 11x11 13x13 15x15 17x17 19x19 21x21 23x23 25x25
+```
+
 ### Sample Output
 ```
 $ battlesnake play --width 3 --height 3 --url http://redacted:4567/ --url http://redacted:4568/  --name Bob --name Sue

cli/commands/info.go

@@ -0,0 +1,78 @@
+package commands
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/BattlesnakeOfficial/rules/maps"
+	"github.com/spf13/cobra"
+)
+
+type mapInfo struct {
+	All bool
+}
+
+func NewMapInfoCommand() *cobra.Command {
+	info := mapInfo{}
+	var infoCmd = &cobra.Command{
+		Use:   "info [flags] map_name [...map_name]",
+		Short: "Display metadata for given map(s)",
+		Long:  "Display metadata for given map(s)",
+		Run: func(cmd *cobra.Command, args []string) {
+			// handle --all flag first as there would be no args
+			if info.All {
+				mapList := maps.List()
+				for i, m := range mapList {
+					info.display(m)
+					if i < (len(mapList) - 1) {
+						fmt.Print("\n")
+					}
+				}
+				return
+			}
+
+			// display help when no map(s) provided via args
+			if len(args) < 1 {
+				err := cmd.Help()
+				if err != nil {
+					log.Fatal(err)
+				}
+				return
+			}
+
+			// display all maps via command args
+			for i, m := range args {
+				info.display(m)
+				if i < (len(args) - 1) {
+					fmt.Print("\n")
+				}
+			}
+
+		},
+	}
+
+	infoCmd.Flags().BoolVarP(&info.All, "all", "a", false, "Display information for all maps")
+
+	return infoCmd
+}
+
+func (m *mapInfo) display(id string) {
+	gameMap, err := maps.GetMap(id)
+	if err != nil {
+		log.Fatalf("Failed to load game map %#v: %v", id, err)
+	}
+	meta := gameMap.Meta()
+	fmt.Println("Name:", meta.Name)
+	fmt.Println("Author:", meta.Author)
+	fmt.Println("Description:", meta.Description)
+	fmt.Println("Version:", meta.Version)
+	fmt.Println("Min Players:", meta.MinPlayers)
+	fmt.Println("Max Players:", meta.MaxPlayers)
+	fmt.Print("Board Sizes (WxH):")
+	for i, s := range meta.BoardSizes {
+		fmt.Printf(" %dx%d", s.Width, s.Height)
+		if i == (len(meta.BoardSizes) - 1) {
+			fmt.Print("\n")
+		}
+	}
+}

cli/commands/list.go

@@ -0,0 +1,22 @@
+package commands
+
+import (
+	"fmt"
+
+	"github.com/BattlesnakeOfficial/rules/maps"
+	"github.com/spf13/cobra"
+)
+
+func NewMapListCommand() *cobra.Command {
+	var listCmd = &cobra.Command{
+		Use:   "list",
+		Short: "List available game maps",
+		Long:  "List available game maps",
+		Run: func(cmd *cobra.Command, args []string) {
+			for _, m := range maps.List() {
+				fmt.Println(m)
+			}
+		},
+	}
+	return listCmd
+}

cli/commands/map.go

@@ -0,0 +1,24 @@
+package commands
+
+import (
+	"log"
+
+	"github.com/spf13/cobra"
+)
+
+func NewMapCommand() *cobra.Command {
+
+	var mapCmd = &cobra.Command{
+		Use:   "map",
+		Short: "Display map information",
+		Long:  "Display map information",
+		Run: func(cmd *cobra.Command, args []string) {
+			err := cmd.Help()
+			if err != nil {
+				log.Fatal(err)
+			}
+		},
+	}
+
+	return mapCmd
+}

cli/commands/root.go

@@ -21,6 +21,12 @@ var rootCmd = &cobra.Command{
 func Execute() {
 	rootCmd.AddCommand(NewPlayCommand())
 
+	mapCommand := NewMapCommand()
+	mapCommand.AddCommand(NewMapListCommand())
+	mapCommand.AddCommand(NewMapInfoCommand())
+
+	rootCmd.AddCommand(mapCommand)
+
 	if err := rootCmd.Execute(); err != nil {
 		fmt.Println(err)
 		os.Exit(1)

maps/registry.go

@@ -2,6 +2,7 @@ package maps
 
 import (
 	"fmt"
+	"sort"
 
 	"github.com/BattlesnakeOfficial/rules"
 )
@@ -21,6 +22,16 @@ func (registry MapRegistry) RegisterMap(id string, m GameMap) {
 	registry[id] = m
 }
 
+// List returns all registered map IDs in alphabetical order
+func (registry MapRegistry) List() []string {
+	var keys []string
+	for k, _ := range registry {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	return keys
+}
+
 // GetMap returns the map associated with the given ID.
 func (registry MapRegistry) GetMap(id string) (GameMap, error) {
 	if m, ok := registry[id]; ok {
@@ -34,6 +45,11 @@ func GetMap(id string) (GameMap, error) {
 	return globalRegistry.GetMap(id)
 }
 
+// List returns a list of maps registered to the global registry.
+func List() []string {
+	return globalRegistry.List()
+}
+
 // RegisterMap adds a map to the global registry.
 func RegisterMap(id string, m GameMap) {
 	globalRegistry.RegisterMap(id, m)

maps/registry_test.go

@@ -112,3 +112,15 @@ func pickSize(meta Metadata) Dimensions {
 	// For fixed, just pick the first supported size
 	return meta.BoardSizes[0]
 }
+
+func TestListRegisteredMaps(t *testing.T) {
+	keys := globalRegistry.List()
+	mapCount := 0
+	for k := range globalRegistry {
+		// every registry key should exist in List results
+		require.Contains(t, keys, k)
+		mapCount++
+	}
+	// List should equal number of maps in the global registry
+	require.Equal(t, len(keys), mapCount)
+}