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1--- The commands API allows your system to directly execute [Minecraft
2-- commands][mc] and gather data from the results.
3--
4-- While one may use @{commands.exec} directly to execute a command, the
5-- commands API also provides helper methods to execute every command. For
6-- instance, `commands.say("Hi!")` is equivalent to `commands.exec("say Hi!")`.
7--
8-- @{commands.async} provides a similar interface to execute asynchronous
9-- commands. `commands.async.say("Hi!")` is equivalent to
10-- `commands.execAsync("Hi!")`.
11--
12-- [mc]: https://minecraft.gamepedia.com/Commands
13--
14-- @module commands
15-- @usage Set the block above this computer to stone:
16--
17--     commands.setblock("~", "~1", "~", "minecraft:stone")
18
19if not commands then
20    error("Cannot load command API on normal computer", 2)
21end
22
23--- The builtin commands API, without any generated command helper functions
24--
25-- This may be useful if a built-in function (such as @{commands.list}) has been
26-- overwritten by a command.
27local native = commands.native or commands
28
29local function collapseArgs(bJSONIsNBT, ...)
30    local args = table.pack(...)
31    for i = 1, #args do
32        local arg = args[i]
33        if type(arg) == "boolean" or type(arg) == "number" or type(arg) == "string" then
34            args[i] = tostring(arg)
35        elseif type(arg) == "table" then
36            args[i] = textutils.serialiseJSON(arg, bJSONIsNBT)
37        else
38            error("Expected string, number, boolean or table", 3)
39        end
40    end
41
42    return table.concat(args, " ")
43end
44
45-- Put native functions into the environment
46local env = _ENV
47env.native = native
48for k, v in pairs(native) do
49    env[k] = v
50end
51
52-- Create wrapper functions for all the commands
53local tAsync = {}
54local tNonNBTJSONCommands = {
55    ["tellraw"] = true,
56    ["title"] = true,
57}
58
59local command_mt = {}
60function command_mt.__call(self, ...)
61    local meta = self[command_mt]
62    local sCommand = collapseArgs(meta.json, table.concat(meta.name, " "), ...)
63    return meta.func(sCommand)
64end
65
66function command_mt.__tostring(self)
67    local meta = self[command_mt]
68    return ("command %q"):format("/" .. table.concat(meta.name, " "))
69end
70
71local function mk_command(name, json, func)
72    return setmetatable({
73        [command_mt] = {
74            name = name,
75            func = func,
76            json = json,
77        },
78    }, command_mt)
79end
80
81function command_mt.__index(self, key)
82    local meta = self[command_mt]
83    if meta.children then return nil end
84    meta.children = true
85
86    local name = meta.name
87    for _, child in ipairs(native.list(table.unpack(name))) do
88        local child_name = { table.unpack(name) }
89        child_name[#child_name + 1] = child
90        self[child] = mk_command(child_name, meta.json, meta.func)
91    end
92
93    return self[key]
94end
95
96for _, sCommandName in ipairs(native.list()) do
97    if env[sCommandName] == nil then
98        local bJSONIsNBT = tNonNBTJSONCommands[sCommandName] == nil
99        env[sCommandName] = mk_command({ sCommandName }, bJSONIsNBT, native.exec)
100        tAsync[sCommandName] = mk_command({ sCommandName }, bJSONIsNBT, native.execAsync)
101    end
102end
103
104--- A table containing asynchronous wrappers for all commands.
105--
106-- As with @{commands.execAsync}, this returns the "task id" of the enqueued
107-- command.
108-- @see execAsync
109-- @usage Asynchronously sets the block above the computer to stone.
110--
111--     commands.async.setblock("~", "~1", "~", "minecraft:stone")
112env.async = tAsync