abstract AbstractCmd

type Cmd <: AbstractCmd
    exec::Vector{ByteString}
    ignorestatus::Bool
    detach::Bool
    env::Union(Array{ByteString},Nothing)
    dir::UTF8String
    Cmd(exec::Vector{ByteString}) = new(exec, false, false, nothing, "")
end

type OrCmds <: AbstractCmd
    a::AbstractCmd
    b::AbstractCmd
    OrCmds(a::AbstractCmd, b::AbstractCmd) = new(a, b)
end

type ErrOrCmds <: AbstractCmd
    a::AbstractCmd
    b::AbstractCmd
    ErrOrCmds(a::AbstractCmd, b::AbstractCmd) = new(a, b)
end

type AndCmds <: AbstractCmd
    a::AbstractCmd
    b::AbstractCmd
    AndCmds(a::AbstractCmd, b::AbstractCmd) = new(a, b)
end

shell_escape(cmd::Cmd) = shell_escape(cmd.exec...)

function show(io::IO, cmd::Cmd)
    print_env = cmd.env !== nothing
    print_dir = !isempty(cmd.dir)
    (print_env || print_dir) && print(io, "setenv(")
    esc = shell_escape(cmd)
    print(io, '`')
    for c in esc
        if c == '`'
            print(io, '\\')
        end
        print(io, c)
    end
    print(io, '`')
    print_env && (print(io, ","); show(io, cmd.env))
    print_dir && (print(io, "; dir="); show(io, cmd.dir))
    (print_dir || print_env) && print(io, ")")
end

function show(io::IO, cmds::OrCmds)
    if isa(cmds.a, AndCmds) || isa(cmds.a, CmdRedirect)
        print(io, "(")
        show(io, cmds.a)
        print(io, ")")
    else
        show(io, cmds.a)
    end
    print(io, " |> ")
    if isa(cmds.b, AndCmds) || isa(cmds.b, CmdRedirect)
        print(io, "(")
        show(io, cmds.b)
        print(io, ")")
    else
        show(io, cmds.b)
    end
end

function show(io::IO, cmds::AndCmds)
    if isa(cmds.a, OrCmds) || isa(cmds.a, CmdRedirect)
        print(io, "(")
        show(io, cmds.a)
        print(io, ")")
    else
        show(io, cmds.a)
    end
    print(io, " & ")
    if isa(cmds.b, OrCmds) || isa(cmds.b, CmdRedirect)
        print(io, "(")
        show(io, cmds.b)
        print(io, ")")
    else
        show(io, cmds.b)
    end
end

const STDIN_NO  = 0
const STDOUT_NO = 1
const STDERR_NO = 2

immutable FileRedirect
    filename::String
    append::Bool
    function FileRedirect(filename, append)
        if lowercase(filename) == (@unix? "/dev/null" : "nul")
            warn_once("for portability use DevNull instead of a file redirect")
        end
        new(filename, append)
    end
end

immutable DevNullStream <: AsyncStream end
const DevNull = DevNullStream()
copy(::DevNullStream) = DevNull
uvhandle(::DevNullStream) = C_NULL
uvhandle(x::Ptr) = x
uvtype(::Ptr) = UV_STREAM
uvtype(::DevNullStream) = UV_STREAM

# Not actually a pointer, but that's how we pass it through the C API
# so it's fine
uvhandle(x::RawFD) = convert(Ptr{Void}, x.fd)
uvtype(x::RawFD) = UV_RAW_FD

typealias Redirectable Union(UVStream, FS.File, FileRedirect, DevNullStream, IOStream, RawFD)

type CmdRedirect <: AbstractCmd
    cmd::AbstractCmd
    handle::Redirectable
    stream_no::Int
end

function show(io::IO, cr::CmdRedirect)
    if cr.stream_no == STDOUT_NO
        show(io, cr.cmd)
        print(io, " |> ")
        show(io, cr.handle)
    elseif cr.stream_no == STDERR_NO
        show(io, cr.cmd)
        print(io, " .> ")
        show(io, cr.handle)
    elseif cr.stream_no == STDIN_NO
        show(io, cr.handle)
        print(io, " |> ")
        show(io, cr.cmd)
    end
end


ignorestatus(cmd::Cmd) = (cmd.ignorestatus=true; cmd)
ignorestatus(cmd::Union(OrCmds,AndCmds)) = (ignorestatus(cmd.a); ignorestatus(cmd.b); cmd)
detach(cmd::Cmd) = (cmd.detach=true; cmd)

setenv{S<:ByteString}(cmd::Cmd, env::Array{S}; dir="") = (cmd.env = ByteString[x for x in env]; setenv(cmd, dir=dir); cmd)
setenv(cmd::Cmd, env::Associative; dir="") = (cmd.env = ByteString[string(k)*"="*string(v) for (k,v) in env]; setenv(cmd, dir=dir); cmd)
setenv(cmd::Cmd; dir="") = (cmd.dir = dir; cmd)

(&)(left::AbstractCmd, right::AbstractCmd) = AndCmds(left, right)
(|>)(src::AbstractCmd, dest::AbstractCmd) = OrCmds(src, dest)
(.>)(src::AbstractCmd, dest::AbstractCmd) = ErrOrCmds(src, dest)

# Stream Redirects
(|>)(dest::Redirectable, src::AbstractCmd) = CmdRedirect(src, dest, STDIN_NO)
(|>)(src::AbstractCmd, dest::Redirectable) = CmdRedirect(src, dest, STDOUT_NO)
(.>)(src::AbstractCmd, dest::Redirectable) = CmdRedirect(src, dest, STDERR_NO)

# File redirects
(|>)(src::AbstractCmd, dest::String) = CmdRedirect(src, FileRedirect(dest, false), STDOUT_NO)
(|>)(src::String, dest::AbstractCmd) = CmdRedirect(dest, FileRedirect(src, false), STDIN_NO)
(.>)(src::AbstractCmd, dest::String) = CmdRedirect(src, FileRedirect(dest, false), STDERR_NO)
(>>)(src::AbstractCmd, dest::String) = CmdRedirect(src, FileRedirect(dest, true), STDOUT_NO)
(.>>)(src::AbstractCmd, dest::String) = CmdRedirect(src, FileRedirect(dest, true), STDERR_NO)


typealias RawOrBoxedHandle Union(UVHandle,UVStream,Redirectable,IOStream)
typealias StdIOSet NTuple{3,RawOrBoxedHandle}

type Process
    cmd::Cmd
    handle::Ptr{Void}
    in::AsyncStream
    out::AsyncStream
    err::AsyncStream
    exitcode::Int32
    termsignal::Int32
    exitcb::Callback
    exitnotify::Condition
    closecb::Callback
    closenotify::Condition
    function Process(cmd::Cmd, handle::Ptr{Void}, in::RawOrBoxedHandle, out::RawOrBoxedHandle, err::RawOrBoxedHandle)
        if !isa(in, AsyncStream) || in === DevNull
            in=DevNull
        end
        if !isa(out, AsyncStream) || out === DevNull
            out=DevNull
        end
        if !isa(err, AsyncStream) || err === DevNull
            err=DevNull
        end
        this = new(cmd, handle, in, out, err, typemin(Int32), typemin(Int32), false, Condition(), false, Condition())
        finalizer(this, uvfinalize)
        this
    end
end

type ProcessChain
    processes::Vector{Process}
    in::Redirectable
    out::Redirectable
    err::Redirectable
    ProcessChain(stdios::StdIOSet) = new(Process[], stdios[1], stdios[2], stdios[3])
end
typealias ProcessChainOrNot Union(Bool,ProcessChain)

function _jl_spawn(cmd::Ptr{Uint8}, argv::Ptr{Ptr{Uint8}}, loop::Ptr{Void}, pp::Process,
                   in, out, err)
    proc = c_malloc(_sizeof_uv_process)
    error = ccall(:jl_spawn, Int32,
        (Ptr{Uint8}, Ptr{Ptr{Uint8}}, Ptr{Void}, Ptr{Void}, Any, Int32,
         Ptr{Void},    Int32,       Ptr{Void},     Int32,       Ptr{Void},
         Int32, Ptr{Ptr{Uint8}}, Ptr{Uint8}),
         cmd,        argv,            loop,      proc,      pp,  uvtype(in),
         uvhandle(in), uvtype(out), uvhandle(out), uvtype(err), uvhandle(err),
         pp.cmd.detach, pp.cmd.env === nothing ? C_NULL : pp.cmd.env, isempty(pp.cmd.dir) ? C_NULL : pp.cmd.dir)
    if error != 0
        disassociate_julia_struct(proc)
        ccall(:jl_forceclose_uv, Void, (Ptr{Void},), proc)
        throw(UVError("could not spawn "*string(pp.cmd), error))
    end
    associate_julia_struct(proc, pp)
    return proc
end

function uvfinalize(proc::Process)
    proc.handle != C_NULL && ccall(:jl_close_uv, Void, (Ptr{Void},), proc.handle)
    disassociate_julia_struct(proc)
    proc.handle = 0
end

function _uv_hook_return_spawn(proc::Process, exit_status::Int64, termsignal::Int32)
    proc.exitcode = exit_status
    proc.termsignal = termsignal
    if isa(proc.exitcb, Function) proc.exitcb(proc, exit_status, termsignal) end
    ccall(:jl_close_uv, Void, (Ptr{Void},), proc.handle)
    notify(proc.exitnotify)
end

function _uv_hook_close(proc::Process)
    proc.handle = 0
    if isa(proc.closecb, Function) proc.closecb(proc) end
    notify(proc.closenotify)
end

function spawn(pc::ProcessChainOrNot, redirect::CmdRedirect, stdios::StdIOSet, exitcb::Callback, closecb::Callback)
    spawn(pc, redirect.cmd, (redirect.stream_no == STDIN_NO  ? redirect.handle : stdios[1],
                             redirect.stream_no == STDOUT_NO ? redirect.handle : stdios[2],
                             redirect.stream_no == STDERR_NO ? redirect.handle : stdios[3]), exitcb, closecb)
end

function spawn(pc::ProcessChainOrNot, cmds::OrCmds, stdios::StdIOSet, exitcb::Callback, closecb::Callback)
    out_pipe = box(Ptr{Void}, Intrinsics.jl_alloca(_sizeof_uv_named_pipe))
    in_pipe = box(Ptr{Void}, Intrinsics.jl_alloca(_sizeof_uv_named_pipe))
    #out_pipe = c_malloc(_sizeof_uv_named_pipe)
    #in_pipe = c_malloc(_sizeof_uv_named_pipe)
    link_pipe(in_pipe, false, out_pipe, false)
    if pc == false
        pc = ProcessChain(stdios)
    end
    try
        spawn(pc, cmds.a, (stdios[1], out_pipe, stdios[3]), exitcb, closecb)
        spawn(pc, cmds.b, (in_pipe, stdios[2], stdios[3]), exitcb, closecb)
    catch err
        close_pipe_sync(out_pipe)
        close_pipe_sync(in_pipe)
        rethrow(err)
    end
    close_pipe_sync(out_pipe)
    close_pipe_sync(in_pipe)
    pc
end

function spawn(pc::ProcessChainOrNot, cmds::ErrOrCmds, stdios::StdIOSet, exitcb::Callback, closecb::Callback)
    out_pipe = box(Ptr{Void}, Intrinsics.jl_alloca(_sizeof_uv_named_pipe))
    in_pipe = box(Ptr{Void}, Intrinsics.jl_alloca(_sizeof_uv_named_pipe))
    #out_pipe = c_malloc(_sizeof_uv_named_pipe)
    #in_pipe = c_malloc(_sizeof_uv_named_pipe)
    link_pipe(in_pipe, false, out_pipe, false)
    if pc == false
        pc = ProcessChain(stdios)
    end
    try
        spawn(pc, cmds.a, (stdios[1], stdios[2], out_pipe), exitcb, closecb)
        spawn(pc, cmds.b, (in_pipe, stdios[2], stdios[3]), exitcb, closecb)
    catch err
        close_pipe_sync(out_pipe)
        close_pipe_sync(in_pipe)
        rethrow(err)
    end
    close_pipe_sync(out_pipe)
    close_pipe_sync(in_pipe)
    pc
end


macro setup_stdio()
    esc(
    quote
        close_in,close_out,close_err = false,false,false
        in,out,err = stdios
        if isa(stdios[1], Pipe)
            if stdios[1].handle == C_NULL
                error("pipes passed to spawn must be initialized")
            end
        elseif isa(stdios[1], FileRedirect)
            in = FS.open(stdios[1].filename, JL_O_RDONLY)
            close_in = true
        elseif isa(stdios[1], IOStream)
            in = FS.File(RawFD(fd(stdios[1])))
        end
        if isa(stdios[2], Pipe)
            if stdios[2].handle == C_NULL
                error("pipes passed to spawn must be initialized")
            end
        elseif isa(stdios[2], FileRedirect)
            out = FS.open(stdios[2].filename, JL_O_WRONLY | JL_O_CREAT | (stdios[2].append?JL_O_APPEND:JL_O_TRUNC), S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
            close_out = true
        elseif isa(stdios[2], IOStream)
            out = FS.File(RawFD(fd(stdios[2])))
        end
        if isa(stdios[3], Pipe)
            if stdios[3].handle == C_NULL
                error("pipes passed to spawn must be initialized")
            end
        elseif isa(stdios[3], FileRedirect)
            err = FS.open(stdios[3].filename, JL_O_WRONLY | JL_O_CREAT | (stdios[3].append?JL_O_APPEND:JL_O_TRUNC), S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
            close_err = true
        elseif isa(stdios[3], IOStream)
            err = FS.File(RawFD(fd(stdios[3])))
        end
    end)
end

macro cleanup_stdio()
    esc(
    quote
        close_in && close(in)
        close_out && close(out)
        close_err && close(err)
    end)
end

function spawn(pc::ProcessChainOrNot, cmd::Cmd, stdios::StdIOSet, exitcb::Callback, closecb::Callback)
    loop = eventloop()
    pp = Process(cmd, C_NULL, stdios[1], stdios[2], stdios[3]);
    @setup_stdio
    ptrs = _jl_pre_exec(cmd.exec)
    pp.exitcb = exitcb
    pp.closecb = closecb
    pp.handle = _jl_spawn(ptrs[1], convert(Ptr{Ptr{Uint8}}, ptrs), loop, pp,
                          in, out, err)
    @cleanup_stdio
    if isa(pc, ProcessChain)
        push!(pc.processes, pp)
    end
    pp
end

function spawn(pc::ProcessChainOrNot, cmds::AndCmds, stdios::StdIOSet, exitcb::Callback, closecb::Callback)
    if pc == false
        pc = ProcessChain(stdios)
    end
    @setup_stdio
    spawn(pc, cmds.a, (in,out,err), exitcb, closecb)
    spawn(pc, cmds.b, (in,out,err), exitcb, closecb)
    @cleanup_stdio
    pc
end

# INTERNAL
# returns a tuple of function arguments to spawn:
# (stdios, exitcb, closecb)
# |       |        \ The function to be called once the uv handle is closed
# |       \ The function to be called once the process exits
# \ A set of up to 256 stdio instructions, where each entry can be either:
#   | - An AsyncStream to be passed to the child
#   | - DevNull to pass /dev/null
#   | - An FS.File object to redirect the output to
#   \ - An ASCIIString specifying a filename to be opened

spawn_opts_swallow(stdios::StdIOSet, exitcb::Callback=false, closecb::Callback=false) =
    (stdios,exitcb,closecb)
spawn_opts_swallow(in::Redirectable=DevNull, out::Redirectable=DevNull, err::Redirectable=DevNull, args...) =
    (tuple(in,out,err,args...),false,false)
spawn_opts_inherit(stdios::StdIOSet, exitcb::Callback=false, closecb::Callback=false) =
    (stdios,exitcb,closecb)
spawn_opts_inherit(in::Redirectable=STDIN, out::Redirectable=STDOUT, err::Redirectable=STDERR, args...) =
    (tuple(in,out,err,args...),false,false)

spawn(pc::ProcessChainOrNot, cmds::AbstractCmd, args...) = spawn(pc, cmds, spawn_opts_swallow(args...)...)
spawn(cmds::AbstractCmd, args...) = spawn(false, cmds, spawn_opts_swallow(args...)...)

macro tmp_rpipe(pipe, tmppipe, code, args...)
    esc(quote
        $pipe = Pipe(C_NULL)
        $tmppipe = Pipe(C_NULL)
        link_pipe($pipe, true, $tmppipe, false)
        r = begin
            $code
        end
        close_pipe_sync($tmppipe)
        r
    end)
end

macro tmp_wpipe(tmppipe, pipe, code)
    esc(quote
        $pipe = Pipe(C_NULL)
        $tmppipe = Pipe(C_NULL)
        link_pipe($tmppipe, false, $pipe, true)
        r = begin
            $code
        end
        close_pipe_sync($tmppipe)
        r
    end)
end

function eachline(cmd::AbstractCmd, stdin)
    @tmp_rpipe out tmp begin
        processes = spawn(false, cmd, (stdin,tmp,STDERR))
        # implicitly close after reading lines, since we opened
        EachLine(out, ()->close(out))
    end
end
eachline(cmd::AbstractCmd) = eachline(cmd, DevNull)

# return a (Pipe,Process) pair to write/read to/from the pipeline
function open(cmds::AbstractCmd, mode::String="r", stdio::AsyncStream=DevNull)
    if mode == "r"
        processes = @tmp_rpipe out tmp spawn(false, cmds, (stdio,tmp,STDERR))
        start_reading(out)
        (out, processes)
    elseif mode == "w"
        processes = @tmp_wpipe tmp inpipe spawn(false, cmds, (tmp,stdio,STDERR))
        (inpipe, processes)
    else
        throw(ArgumentError("mode must be \"r\" or \"w\", not \"$mode\""))
    end
end

function open(f::Function, cmds::AbstractCmd, args...)
    io, P = open(cmds, args...)
    ret = try
        f(io)
    catch
        kill(P)
        rethrow()
    finally
        close(io)
    end
    success(P) || pipeline_error(P)
    return ret
end

# TODO: convert this to use open(cmd, "r+"), with a single read/write pipe
function readandwrite(cmds::AbstractCmd)
    (out, processes) = @tmp_wpipe tmp inpipe open(cmds, "r", tmp)
    (out, inpipe, processes)
end

function readbytes(cmd::AbstractCmd, stdin::AsyncStream=DevNull)
    (out,pc) = open(cmd, "r", stdin)
    !success(pc) && pipeline_error(pc)
    wait_close(out)
    return takebuf_array(out.buffer)
end

function readall(cmd::AbstractCmd, stdin::AsyncStream=DevNull)
    return bytestring(readbytes(cmd, stdin))
end

function writeall(cmd::AbstractCmd, stdin::String, stdout::AsyncStream=DevNull)
    open(cmd, "w", stdout) do io
        write(io, stdin)
    end
end

function run(cmds::AbstractCmd, args...)
    ps = spawn(cmds, spawn_opts_inherit(args...)...)
    success(ps) ? nothing : pipeline_error(ps)
end

const SIGPIPE = 13
function test_success(proc::Process)
    assert(process_exited(proc))
    if proc.exitcode < 0
        error(UVError("could not start process "*string(proc.cmd), proc.exitcode))
    end
    proc.exitcode == 0 && (proc.termsignal == 0 || proc.termsignal == SIGPIPE)
end

function success(x::Process)
    wait(x)
    kill(x)
    test_success(x)
end
success(procs::Vector{Process}) = mapreduce(success, &, procs)
success(procs::ProcessChain) = success(procs.processes)
success(cmd::AbstractCmd) = success(spawn(cmd))

function pipeline_error(proc::Process)
    if !proc.cmd.ignorestatus
        error("failed process: ", proc, " [", proc.exitcode, "]")
    end
    nothing
end

function pipeline_error(procs::ProcessChain)
    failed = Process[]
    for p = procs.processes
        if !test_success(p) && !p.cmd.ignorestatus
            push!(failed, p)
        end
    end
    length(failed) == 0 && return nothing
    length(failed) == 1 && pipeline_error(failed[1])
    msg = "failed processes:"
    for proc in failed
        msg = string(msg, "\n  ", proc, " [", proc.exitcode, "]")
    end
    error(msg)
end

_jl_kill(p::Process, signum::Integer) = ccall(:uv_process_kill, Int32, (Ptr{Void},Int32), p.handle, signum)
function kill(p::Process, signum::Integer)
    if process_running(p)
        @assert p.handle != C_NULL
        _jl_kill(p, signum)
    else
        int32(-1)
    end
end
kill(ps::Vector{Process}) = map(kill, ps)
kill(ps::ProcessChain) = map(kill, ps.processes)
kill(p::Process) = kill(p, 15) #SIGTERM

function _contains_newline(bufptr::Ptr{Void}, len::Int32)
    return (ccall(:memchr, Ptr{Void}, (Ptr{Void},Int32,Csize_t), bufptr, '\n', len) != C_NULL)
end

## process status ##
process_running(s::Process) = s.exitcode == typemin(Int32)
process_running(s::Vector{Process}) = any(process_running, s)
process_running(s::ProcessChain) = process_running(s.processes)

process_exited(s::Process) = !process_running(s)
process_exited(s::Vector{Process}) = all(process_exited, s)
process_exited(s::ProcessChain) = process_exited(s.processes)

process_signaled(s::Process) = (s.termsignal > 0)

#process_stopped (s::Process) = false #not supported by libuv. Do we need this?
#process_stop_signal(s::Process) = false #not supported by libuv. Do we need this?

function process_status(s::Process)
    process_running (s) ? "ProcessRunning" :
    process_signaled(s) ? "ProcessSignaled("*string(s.termsignal)*")" :
    #process_stopped (s) ? "ProcessStopped("*string(process_stop_signal(s))*")" :
    process_exited  (s) ? "ProcessExited("*string(s.exitcode)*")" :
    error("process status error")
end

# WARNING: do not call this and keep the returned array of pointers
# around longer than the args vector and then use array of pointers.
# this could cause a segfault. this is really just for use by the
# spawn function below so that we can exec more efficiently.
#
function _jl_pre_exec(args::Vector{ByteString})
    if length(args) < 1
        error("too few arguments to exec")
    end
    ptrs = Array(Ptr{Uint8}, length(args)+1)
    for i = 1:length(args)
        ptrs[i] = args[i].data
    end
    ptrs[length(args)+1] = C_NULL
    return ptrs
end

## implementation of `cmd` syntax ##

arg_gen()          = ByteString[]
arg_gen(x::String) = ByteString[x]
arg_gen(cmd::Cmd)  = cmd.exec

function arg_gen(head)
    if applicable(start, head)
        vals = ByteString[]
        for x in head
            push!(vals, string(x))
        end
        return vals
    else
        return ByteString[string(head)]
    end
end

function arg_gen(head, tail...)
    head = arg_gen(head)
    tail = arg_gen(tail...)
    vals = ByteString[]
    for h = head, t = tail
        push!(vals, bytestring(h, t))
    end
    vals
end

function cmd_gen(parsed)
    args = ByteString[]
    for arg in parsed
        append!(args, arg_gen(arg...))
    end
    Cmd(args)
end

macro cmd(str)
    :(cmd_gen($(shell_parse(str)[1])))
end

wait(x::Process)      = if !process_exited(x); stream_wait(x, x.exitnotify); end
wait(x::ProcessChain) = for p in x.processes; wait(p); end

show(io::IO, p::Process) = print(io, "Process(", p.cmd, ", ", process_status(p), ")")