local nvimsrcdir = arg[1]
local includedir = arg[2]
local autodir = arg[3]

if nvimsrcdir == '--help' then
  print ([[
Usage:
  lua genex_cmds.lua src/nvim build/include build/src/nvim/auto

Will generate files build/include/ex_cmds_enum.generated.h with cmdidx_T
enum and build/src/nvim/auto/ex_cmds_defs.generated.h with main Ex commands
definitions.
]])
  os.exit(0)
end

package.path = nvimsrcdir .. '/?.lua;' .. package.path

local enumfname = includedir .. '/ex_cmds_enum.generated.h'
local defsfname = autodir .. '/ex_cmds_defs.generated.h'

local enumfile = io.open(enumfname, 'w')
local defsfile = io.open(defsfname, 'w')

local defs = require('ex_cmds')

local first = true

local byte_a = string.byte('a')
local byte_z = string.byte('z')
local a_to_z = byte_z - byte_a + 1

-- Table giving the index of the first command in cmdnames[] to lookup
-- based on the first letter of a command.
local cmdidxs1_out = string.format([[
static const uint16_t cmdidxs1[%u] = {
]], a_to_z)
-- Table giving the index of the first command in cmdnames[] to lookup
-- based on the first 2 letters of a command.
-- Values in cmdidxs2[c1][c2] are relative to cmdidxs1[c1] so that they
-- fit in a byte.
local cmdidxs2_out = string.format([[
static const char_u cmdidxs2[%u][%u] = {
/*             a   b   c   d   e   f   g   h   i   j   k   l   m   n   o   p   q   r   s   t   u   v   w   x   y   z */

]], a_to_z, a_to_z)

enumfile:write([[
typedef enum CMD_index {
]])
defsfile:write(string.format([[
static const int command_count = %u;
]], #defs))
defsfile:write(string.format([[
static CommandDefinition cmdnames[%u] = {
]], #defs))
local cmds, cmdidxs1, cmdidxs2 = {}, {}, {}
for _, cmd in ipairs(defs) do
  local enumname = cmd.enum or ('CMD_' .. cmd.command)
  local byte_cmd = cmd.command:sub(1, 1):byte()
  if byte_a <= byte_cmd and byte_cmd <= byte_z then
    table.insert(cmds, cmd.command)
  end
  if first then
    first = false
  else
    defsfile:write(',\n')
  end
  enumfile:write('  ' .. enumname .. ',\n')
  defsfile:write(string.format([[
  [%s] = {
    .cmd_name = (char_u *) "%s",
    .cmd_func = (ex_func_T)&%s,
    .cmd_argt = %uL,
    .cmd_addr_type = %i
  }]], enumname, cmd.command, cmd.func, cmd.flags, cmd.addr_type))
end
for i = #cmds, 1, -1 do
  local cmd = cmds[i]
  -- First and second characters of the command
  local c1 = cmd:sub(1, 1)
  cmdidxs1[c1] = i - 1
  if cmd:len() >= 2 then
    local c2 = cmd:sub(2, 2)
    local byte_c2 = string.byte(c2)
    if byte_a <= byte_c2 and byte_c2 <= byte_z then
      if not cmdidxs2[c1] then
        cmdidxs2[c1] = {}
      end
      cmdidxs2[c1][c2] = i - 1
    end
  end
end
for i = byte_a, byte_z do
  local c1 = string.char(i)
  cmdidxs1_out = cmdidxs1_out .. '  /*  ' .. c1 .. '  */ ' .. cmdidxs1[c1] .. ',\n'
  cmdidxs2_out = cmdidxs2_out .. '  /*  ' .. c1 .. '  */ {'
  for j = byte_a, byte_z do
    local c2 = string.char(j)
    cmdidxs2_out = cmdidxs2_out ..
      ((cmdidxs2[c1] and cmdidxs2[c1][c2])
        and string.format('%3d', cmdidxs2[c1][c2] - cmdidxs1[c1])
        or '  0') .. ','
  end
  cmdidxs2_out = cmdidxs2_out .. ' },\n'
end
defsfile:write([[

};
]])
enumfile:write([[
  CMD_SIZE,
  CMD_USER = -1,
  CMD_USER_BUF = -2
} cmdidx_T;
]])
defsfile:write(cmdidxs1_out .. '};\n')
defsfile:write(cmdidxs2_out .. '};\n')