cshell

local parentShell = shell

local bExit = false
local sDir = (parentShell and parentShell.dir()) or ""
local sPath = (parentShell and parentShell.path()) or ".:/rom/programs"
local tAliases = (parentShell and parentShell.aliases()) or {}
local tProgramStack = {}

local shell = {}
local tEnv = {
    ["shell"] = shell,
}

-- Install shell API
function shell.run( _sCommand, ... )
    local sPath = shell.resolveProgram( _sCommand )
    if sPath ~= nil then
        tProgramStack[#tProgramStack + 1] = sPath
        local result = os.run( tEnv, sPath, ... )
        tProgramStack[#tProgramStack] = nil
        return result
    else
        print( "No such program" )
        return false
    end
end

function shell.exit()
    bExit = true
end

function shell.dir()
    return sDir
end

function shell.setDir( _sDir )
    sDir = _sDir
end

function shell.path()
    return sPath
end

function shell.setPath( _sPath )
    sPath = _sPath
end

function shell.resolve( _sPath )
    local sStartChar = string.sub( _sPath, 1, 1 )
    if sStartChar == "/" or sStartChar == "\\" then
        return fs.combine( "", _sPath )
    else
        return fs.combine( sDir, _sPath )
    end
end

function shell.resolveProgram( _sCommand )
    -- Substitute aliases firsts
    if tAliases[ _sCommand ] ~= nil then
        _sCommand = tAliases[ _sCommand ]
    end

    -- If the path is a global path, use it directly
    local sStartChar = string.sub( _sCommand, 1, 1 )
    if sStartChar == "/" or sStartChar == "\\" then
        local sPath = fs.combine( "", _sCommand )
        if fs.exists( sPath ) and not fs.isDir( sPath ) then
            return sPath
        end
        return nil
    end

    -- Otherwise, look on the path variable
    for sPath in string.gmatch(sPath, "[^:]+") do
        sPath = fs.combine( shell.resolve( sPath ), _sCommand )
        if fs.exists( sPath ) and not fs.isDir( sPath ) then
            return sPath
        end
    end

    -- Not found
    return nil
end

function shell.programs( _bIncludeHidden )
    local tItems = {}

    -- Add programs from the path
    for sPath in string.gmatch(sPath, "[^:]+") do
        sPath = shell.resolve( sPath )
        if fs.isDir( sPath ) then
            local tList = fs.list( sPath )
            for n,sFile in pairs( tList ) do
                if not fs.isDir( fs.combine( sPath, sFile ) ) and
                   (_bIncludeHidden or string.sub( sFile, 1, 1 ) ~= ".") then
                    tItems[ sFile ] = true
                end
            end
        end
    end

    -- Sort and return
    local tItemList = {}
    for sItem, b in pairs( tItems ) do
        table.insert( tItemList, sItem )
    end
    table.sort( tItemList )
    return tItemList
end

function shell.getRunningProgram()
    if #tProgramStack > 0 then
        return tProgramStack[#tProgramStack]
    end
    return nil
end

function shell.setAlias( _sCommand, _sProgram )
    tAliases[ _sCommand ] = _sProgram
end

function shell.clearAlias( _sCommand )
    tAliases[ _sCommand ] = nil
end

function shell.aliases()
    -- Add aliases
    local tCopy = {}
    for sAlias, sCommand in pairs( tAliases ) do
        tCopy[sAlias] = sCommand
    end
    return tCopy
end

print( os.version() )

-- If this is the toplevel shell, run the startup programs
if parentShell == nil then
    -- Run the startup from the ROM first
    local sRomStartup = shell.resolveProgram( "/rom/startup" )
    if sRomStartup then
        shell.run( sRomStartup )
    end

    -- Then run the user created startup, from the disks or the root
    local sUserStartup = shell.resolveProgram( "/startup2" )


    if sUserStartup then
        shell.run( sUserStartup )
    end
end

-- Run any programs passed in as arguments
local tArgs = { ... }
if #tArgs > 0 then
    shell.run( ... )
end

-- Read commands and execute them
local tCommandHistory = {}
while not bExit do
    write( shell.dir() .. "> " )

    local sLine = read( nil, tCommandHistory )
    table.insert( tCommandHistory, sLine )

    local tWords = {}
    for match in string.gmatch(sLine, "[^ \t]+") do
        table.insert( tWords, match )
    end

    local sCommand = tWords[1]
    if sCommand then
        shell.run( sCommand, unpack( tWords, 2 ) )
    end
end

-- If this is the toplevel shell, run the shutdown program
if parentShell == nil then
    if shell.resolveProgram( "shutdown" ) then
        shell.run( "shutdown" )
    end
    os.shutdown() -- just in case
end