# this is just a simple prompt to test that shit is working

fn pad(s, width) do
  let out = s
  while out:len() < width do out = out ~ " " end
  return out
end

fn help_row(cmd, desc) puts("    #{pad(cmd, 20)}#{desc}\n")

fn cmd_help() do
  puts("\n  shell\n")
  help_row("help", "show this")
  help_row("clear", "wipe the screen")
  help_row("time", "utc clock")
  help_row("mem", "free / total ram")
  help_row("uptime", "seconds since boot")
  help_row("ps", "running processes")
  help_row("zoom in|out", "scale the font")
  help_row("echo <text>", "print it back")
  puts("\n  files\n")
  help_row("ls [path]", "list a directory")
  help_row("cd <path>", "change directory")
  help_row("pwd", "print working dir")
  help_row("mkdir <path>", "make a directory")
  help_row("cat <path>", "print a file")
  help_row("edit <path>", "line editor, . to save")
  help_row("write <path> <text>", "create or overwrite")
  help_row("rm <path>", "delete a file or empty dir")
  help_row("mkfs", "format the disk")
  puts("\n  programs\n")
  help_row("run", "list programs")
  help_row("run <name>", "")
  puts("\n")
end

fn welcome() do
  let fsline = "no filesystem"
  if fs.ready do fsline = "revelfs mounted" end
  puts("\n")
  puts("   kernel written in revo - by an alcoholic\n")
  puts("   #{(mem_total() shr 20)} MiB ram | #{fsline} | #{prog_count()} programs\n")
  puts("   type help to see what it does\n\n% ")
end

fn arg_name(line, start) do
  let quoted = :false
  let begin = start
  if (begin < line:len() and line[begin] == "\"") do begin += 1 quoted = :true end
  let i = begin
  if quoted do
    while (i < line:len() and line[i] != "\"") do i += 1 end
  end
  else do
    while (i < line:len() and line[i] != " ") do i += 1 end
  end
  const name = line[begin..i]
  let rest = i
  if (quoted and rest < line:len()) do rest += 1 end
  if (rest < line:len() and line[rest] == " ") do rest += 1 end
  { name = name, rest = rest }
end

global wd = { path = "/" }

global editor = { active = :false, path = "", buf = "" }

fn editor_start(path) do
  editor.active = :true
  editor.path = path
  editor.buf = ""
  const sz = fs:size(path)
  if sz > 0 do
    editor.buf = fs:read_bytes(path, 0, sz)
    puts(editor.buf)
  end
  puts("-- editing #{path}, a single . on a line saves and exits --\n")
end

fn editor_line(line) do
  if line == "." do
    fs:store(editor.path, editor.buf)
    editor.active = :false
    puts("saved #{editor.path} (#{editor.buf:len()} bytes)\n% ")
  end
  else do editor.buf = editor.buf ~ line ~ "\n" end
end

fn cmd_edit(line) do
  const a = arg_name(line, 5)
  if a.name:len() == 0 do puts("usage: edit <path>\n% ") return :nil end
  editor_start(abspath(a.name))
end

fn abspath(arg) do
  if arg:len() == 0 return wd.path
  let p = arg
  if arg[0] != "/" do
    if wd.path == "/" do p = "/#{arg}" end
    else do p = "#{wd.path}/#{arg}" end
  end
  while (p:len() > 1 and p[p:len() - 1] == "/") do p = p[0..(p:len() - 1)] end
  return p
end

fn parent_of(path) do
  if path == "/" return "/"
  let i = path:len() - 1
  while (i > 0 and path[i] != "/") do i -= 1 end
  if i == 0 return "/"
  return path[0..i]
end

fn cmd_cd(words) do
  const arg = if words:len() > 1 words[1] else "/"
  const target = if arg == ".." parent_of(wd.path) else abspath(arg)
  if target == "/proc" or target == "/bin" or fs:is_dir(target) do wd.path = target end
  else do puts("cd: #{arg}: not a directory\n") end
end

fn cmd_pwd() puts("#{wd.path}\n")

fn cmd_ls(words) do
  const target = if words:len() > 1 abspath(words[1]) else wd.path
  if vfs_owns(target) do vfs_ls(target) return :nil end
  const n = fs:ls(target)
  # the virtual mounts arent real dir entries, overlay them on the root listing
  if target == "/" do puts("  bin/\n  proc/\n") end
  else if n == 0 do puts("  (empty)\n") end
end

fn cmd_mkdir(words) do
  if words:len() < 2 do puts("usage: mkdir <name>\n") return :nil end
  fs:mkdir(abspath(words[1]))
end

fn cmd_write(line) do
  const a = arg_name(line, 6)
  if a.name:len() == 0 do puts("usage: write <name> <text>\n") return :nil end
  fs:write(abspath(a.name), line[a.rest..])
end

fn cmd_cat(line) do
  const a = arg_name(line, 4)
  if a.name:len() == 0 do puts("usage: cat <name>\n") return :nil end
  const p = abspath(a.name)
  if vfs_owns(p) do vfs_cat(p) return :nil end
  fs:cat(p)
end

fn cmd_rm(line) do
  const a = arg_name(line, 3)
  if a.name:len() == 0 do puts("usage: rm <name>\n") return :nil end
  fs:rm(abspath(a.name))
end

fn zoom_by(delta) do
  let scale = con.scale + delta
  if scale < 1 do scale = 1 end
  if scale > 6 do scale = 6 end
  con.scale = scale
  cmd_clear()
  puts("zoom #{scale}x\n")
end

fn cmd_zoom(words) do
  const dir = if words:len() > 1 words[1] else ""
  if dir == "in" do zoom_by(1) end
  else if dir == "out" do zoom_by(-1) end
  else do puts("usage: zoom in | zoom out\n") end
end

fn cmd_clear() con:clear()

fn bcd(byte) (byte shr 4) * 10 + (byte band 15)
fn rtc(reg) do
  outb(0x70, reg)
  inb(0x71)
end
fn cmd_time() puts("utc #{bcd(rtc(4))}:#{bcd(rtc(2))}:#{bcd(rtc(0))}\n")

# 0x prefixed 16 digit hex
fn hex(n) do
  const digits = "0123456789abcdef"
  let out = ""
  for i in 0..16 do out = out ~ digits[(n shr ((15 - i) * 4)) band 15] end
  "0x#{out}"
end

fn mem_type_name(kind) do
  if kind == 0 return "usable"
  if kind == 1 return "reserved"
  if kind == 2 return "acpi-reclaimable"
  if kind == 3 return "acpi-nvs"
  if kind == 4 return "bad"
  if kind == 5 return "bootloader-reclaimable"
  if kind == 6 return "kernel+modules"
  if kind == 7 return "framebuffer"
  "unknown"
end

# the boot memory map dump
fn dump_memmap() do
  puts("memory map:\n")
  for i in 0..memmap_count() do
    puts("  #{hex(memmap_base(i))} len=#{hex(memmap_len(i))} type=#{mem_type_name(memmap_kind(i))}\n")
  end
  puts("usable: #{(mem_total() shr 20)} MiB, free: #{(mem_free() shr 20)} MiB\n")
end

fn cmd_mem() puts("#{(mem_free() shr 20)} MiB free / #{(mem_total() shr 20)} MiB usable\n")
fn cmd_uptime() puts("#{math.floor(uptime() / 100)}s (#{uptime()} ticks)\n")
fn cmd_ps() puts("#{proc_count()} process(es) running\n")

fn run(line) do
  if editor.active do editor_line(line) return :nil end
  if line:trim():len() == 0 do puts("% ") return :nil end
  const words = line:split(" ")
  const cmd = words[0]
  if cmd == "edit" do cmd_edit(line) return :nil end
  if cmd == "run" do
    if words:len() <= 1 do list_progs() puts("% ") return :nil end
    const prog = words[1]
    # everything after "run <prog> " is the programs argument string
    const start = 4 + prog:len() + 1
    const arg = if line:len() > start line[start..] else ""
    if run_prog(prog, arg) == :true return :nil
    puts("% ")
    return :nil
  end
  match cmd
    | "help" => cmd_help()
    | "clear" => cmd_clear()
    | "time" => cmd_time()
    | "mem" => cmd_mem()
    | "uptime" => cmd_uptime()
    | "ps" => cmd_ps()
    | "zoom" => cmd_zoom(words)
    | "mkfs" => fs:format()
    | "ls" => cmd_ls(words)
    | "cat" => cmd_cat(line)
    | "write" => cmd_write(line)
    | "rm" => cmd_rm(line)
    | "mkdir" => cmd_mkdir(words)
    | "cd" => cmd_cd(words)
    | "pwd" => cmd_pwd()
    | "echo" => if line:len() > 5 puts("#{line[5..]}\n") else puts("\n")
    | _ => puts("unknown command: #{cmd}\n")
  puts("% ")
end