local fs=require("filesystem")
local shell=require("shell")
local tty=require("tty")
local computer=require("computer")



local args,options=shell.parse(...)

local gpu=tty.gpu()

local function printUsage(ostream,msg)
local s=ostream or io.stdout
if msg then
s:write(msg,'\n')
end
s:write([[Usage: grep [OPTION]... PATTERN [FILE]...
Example: grep -i "hello world" menu.lua main.lua
for more information, run: man grep
]])
end

local PATTERNS={args[1]}
local FILES={select(2,table.unpack(args))}

local LABEL_COLOR=0xb000b0
local LINE_NUM_COLOR=0x00FF00
local MATCH_COLOR=0xFF0000
local COLON_COLOR=0x00FFFF

local function pop(...)
local result
for _,key in ipairs({...})do
result=options[key]or result
options[key]=nil
end
return result
end


local plain=pop('F','fixed-strings')
plain=not pop('e','--lua-regexp')and plain
local pattern_file=pop('file')
local match_whole_word=pop('w','word-regexp')
local match_whole_line=pop('x','line-regexp')
local ignore_case=pop('i','ignore-case')
local stdin_label=pop('label')or'(standard input)'
local stderr=pop('s','no-messages')and{write=function()end}or io.stderr
local invert_match=not not pop('v','invert-match')


if pop('V','version','help')then
printUsage()
return 0
end

local max_matches=tonumber(pop('max-count'))or math.huge
local print_line_num=pop('n','line-number')
local search_recursively=pop('r','recursive')


if pattern_file then
local pattern_file_path=shell.resolve(pattern_file)
if not fs.exists(pattern_file_path)then
stderr:write('grep: ',pattern_file,': file not found')
return 2
end
table.insert(FILES,1,PATTERNS[1])
PATTERNS={}
for line in io.lines(pattern_file_path)do
PATTERNS[#PATTERNS+1]=line
end
end

if#PATTERNS==0 then
printUsage(stderr)
return 2
end

if#FILES==0 then
FILES=search_recursively and{'.'}or{'-'}
end

if not options.h and search_recursively then
options.H=true
end

if#FILES<2 then
options.h=true
end

local f_only=pop('l','files-with-matches')
local no_only=pop('L','files-without-match')and not f_only

local include_filename=pop('H','with-filename')
include_filename=not pop('h','no-filename')or include_filename

local m_only=pop('o','only-matching')
local quiet=pop('q','quiet','silent')

local print_count=pop('c','count')
local colorize=pop('color','colour')and io.output().tty and tty.isAvailable()

local noop=function(...)return...;end
local setc=colorize and gpu.setForeground or noop
local getc=colorize and gpu.getForeground or noop

local trim=pop('t','trim')
local trim_front=trim and function(s)return s:gsub('^%s+','')end or noop
local trim_back=trim and function(s)return s:gsub('%s+$','')end or noop

if next(options)then
if not quiet then
printUsage(stderr,'unexpected option: '..next(options))
return 2
end
return 0
end

local function resolve(file)
if file:sub(1,1)=='/'then
return fs.canonical(file)
else
if file:sub(1,2)=='./'then
file=file:sub(3,-1)
end
return fs.canonical(fs.concat(shell.getWorkingDirectory(),file))
end
end



if ignore_case then
for i=1,#PATTERNS do

PATTERNS[i]=PATTERNS[i]:gsub("(%%?)(.)",function(percent,letter)
if percent~=""or not letter:match("%a")then

return percent..letter
else
return string.format("[%s%s]",letter:lower(),letter:upper())
end
end)
end
end

local function getAllFiles(dir,file_list)
for node in fs.list(shell.resolve(dir))do
local rel_path=dir:gsub("/+$","")..'/'..node
local resolved_path=shell.resolve(rel_path)
if fs.isDirectory(resolved_path)then
getAllFiles(rel_path,file_list)
else
file_list[#file_list+1]=rel_path
end
end
end

if search_recursively then
local files={}
for i,arg in ipairs(FILES)do
if fs.isDirectory(arg)then
getAllFiles(arg,files)
else
files[#files+1]=arg
end
end
FILES=files
end


local function readLines()
local curHand=nil
local curFile=nil
local meta=nil
return function()
if not curFile then
local file=table.remove(FILES,1)
if not file then
return
end
meta={line_num=0,hits=0}
if file=="-"then
curFile=file
meta.label=stdin_label
curHand=io.input()
else
meta.label=file
local file,reason=resolve(file)
if fs.exists(file)then
curHand,reason=io.open(file,'r')
if not curHand then
local msg=string.format("failed to read from %s: %s",meta.label,reason)
stderr:write("grep: ",msg,"\n")
return false,2
else
curFile=meta.label
end
else
stderr:write("grep: ",file,": file not found\n")
return false,2
end
end
end
meta.line=nil
if not meta.close and curHand then
meta.line_num=meta.line_num+1
meta.line=curHand:read("*l")
end
if not meta.line then
curFile=nil
if curHand then
curHand:close()
end
return false,meta
else
return meta,curFile
end
end
end

local function write(part,color)
local prev_color=color and getc()
if color then setc(color)end
io.write(part)
if color then setc(prev_color)end
end
local flush=(f_only or no_only or print_count)and function(m)
if no_only and m.hits==0 or f_only and m.hits~=0 then
write(m.label,LABEL_COLOR)
write('\n')
elseif print_count then
if include_filename then
write(m.label,LABEL_COLOR)
write(':',COLON_COLOR)
end
write(m.hits)
write('\n')
end
end
local ec=nil
local any_hit_ec=1
local function test(m,p)
local empty_line=true
local last_index,slen=1,#m.line
local needs_filename,needs_line_num=include_filename,print_line_num
local hit_value=1
while last_index<=slen and not m.close do
local i,j=m.line:find(p,last_index,plain)
local word_fail,line_fail=
match_whole_word and not(i and not(m.line:sub(i-1,i-1)..m.line:sub(j+1,j+1)):find("[%a_]")),
match_whole_line and not(i==1 and j==slen)
local matched=not((m_only or last_index==1)and not i)
if(hit_value==1 and word_fail)or line_fail then
matched,i,j=false
end
if invert_match==matched then break end
if max_matches==0 then os.exit(1)end
any_hit_ec=0
m.hits,hit_value=m.hits+hit_value,0
if f_only or no_only then
m.close=true
end
if flush or quiet then return end
if needs_filename then
write(m.label,LABEL_COLOR)
write(':',COLON_COLOR)
needs_filename=nil
end
if needs_line_num then
write(m.line_num,LINE_NUM_COLOR)
write(':',COLON_COLOR)
needs_line_num=nil
end
local s=m_only and''or m.line:sub(last_index,(i or 0)-1)
local g=i and m.line:sub(i,j)or''
if i==1 then g=trim_front(g)elseif last_index==1 then s=trim_front(s)end
if j==slen then g=trim_back(g)elseif not i then s=trim_back(s)end
write(s)
write(g,MATCH_COLOR)
empty_line=false
last_index=(j or slen)+1
if m_only or last_index>slen then
write("\n")
empty_line=true
needs_filename,needs_line_num=include_filename,print_line_num
elseif p:find("^^")and not plain then p="^$"end
end
if not empty_line then write("\n")end
if max_matches~=math.huge and max_matches>=m.hits then
m.close=true
end
end

local uptime=computer.uptime
local last_sleep=uptime()
for meta,status in readLines()do
if uptime()-last_sleep>1 then
os.sleep(0)
last_sleep=uptime()
end
if not meta then
if type(status)=='table'then if flush then
flush(status)end
elseif status then
ec=status or ec
end
else
for _,p in ipairs(PATTERNS)do
test(meta,p)
end
end
end

return ec or any_hit_ec