program day3
    implicit none
    integer, parameter :: max_lines = 200
    integer, parameter :: max_chars = 200
    character(200) :: fname
    integer :: n_arguments
    character(10) :: numbers
    character(11) :: non_symbols
    character(1) :: symb
    integer :: part_sum = 0
    integer :: part_val
    character(max_chars) :: schematic(1:max_lines)
    character(max_chars) :: temp_line
    character(max_chars) :: num_string
    integer :: line, cp0, cp1, cp2, i1, i2, cind 
    integer :: schematic_width, schematic_height
    integer :: istat
    logical :: is_part
    integer, parameter :: max_gears = 10000
    integer :: gear_parts(max_gears, 0:2)
    integer :: found_gears = 0
    integer, allocatable :: gearmap(:,:)
    integer, allocatable :: gearval(:,:)
    integer :: gear_ratio_sum = 0

    n_arguments = command_argument_count()
    if (n_arguments .eq. 1) then
        call get_command_argument(1, fname)
        print *, "File: ", fname
    else
        print *, "Wrong number of arguments: ", n_arguments
        stop
    end if
    do i1=0,9
        numbers(i1+1:i1+1) = char(ichar('0') + i1)
    end do
    non_symbols(1:10) = numbers
    non_symbols(11:11) = "."
    open(10, file=fname)
    do line=1,max_lines
        read(10, "(A)", iostat = istat) temp_line
        if (is_iostat_end(istat)) then
            exit
        else if (len_trim(temp_line) .eq. 0) then
            exit
        else
            schematic(line) = temp_line
        end if
    end do
    schematic_height = line - 1
    schematic_width = len_trim(schematic(1))
    do line=1,schematic_height
        temp_line = schematic(line)
        cp2 = 1
        do
            cp0 = cp2
            cp1 = scan(temp_line(cp0:schematic_width), numbers)
            if (cp1 .eq. 0) then
                exit
            end if
            cp1 = cp1 + cp0 - 1
            cp2 = verify(temp_line(cp1:schematic_width), numbers)
            if (cp2 .eq. 0) then
                cp2 = schematic_width+1
            else
                cp2 = cp2 + cp1 - 1
            end if
            num_string = temp_line(cp1:(cp2-1))
            read(num_string, *) part_val
            i1 = max(1, cp1-1)
            i2 = min(schematic_width, cp2)
            is_part = .false.
            if (line .gt. 1) then
                cind = verify(schematic(line-1)(i1:i2), non_symbols)
                if (cind .ne. 0) then
                    symb = schematic(line-1)(i1 + cind - 1:i1 + cind - 1)
                    print *, line, cp1, symb, part_val
                    part_sum = part_sum + part_val
                    is_part = .true.
                    if (symb .eq. '*') then
                        found_gears = found_gears + 1
                        gear_parts(found_gears, 0) = part_val
                        gear_parts(found_gears, 1) = cind+i1-1
                        gear_parts(found_gears, 2) = line-1
                    end if
                end if
            end if
            cind = verify(schematic(line)(i1:i2), non_symbols)
            if (cind .ne. 0) then
                symb = schematic(line)(i1 + cind - 1:i1 + cind - 1)
                print *, line, cp1, symb, part_val
                if (.not. is_part) then
                    part_sum = part_sum + part_val
                    is_part = .true.
                end if
                if (symb .eq. '*') then
                    found_gears = found_gears + 1
                    gear_parts(found_gears, 0) = part_val
                    gear_parts(found_gears, 1) = cind+i1-1
                    gear_parts(found_gears, 2) = line
                end if
            end if
            if (line .lt. schematic_height) then
                cind = verify(schematic(line+1)(i1:i2), non_symbols)
                if (cind .ne. 0) then
                    symb = schematic(line+1)(i1 + cind - 1:i1 + cind - 1)
                    print *, line, cp1, symb, part_val
                    part_sum = part_sum + part_val
                    if (.not. is_part) then
                        part_sum = part_sum + part_val
                        is_part = .true.
                    end if
                    if (symb .eq. '*') then
                        found_gears = found_gears + 1
                        gear_parts(found_gears, 0) = part_val
                        gear_parts(found_gears, 1) = cind+i1-1
                        gear_parts(found_gears, 2) = line+1
                    end if
                end if
            end if
        end do
    end do
    close(10)
    print *
    print *, "Sum of part numbers: ", part_sum
    print *, "Number of found gears: ", found_gears

    allocate(gearmap(1:schematic_width, 1:schematic_height), source = 0)
    allocate(gearval(1:schematic_width, 1:schematic_height), source = 1)
    do i1=1,found_gears
        cp1 = gear_parts(i1, 1)
        cp2 = gear_parts(i1, 2)
        gearmap(cp1, cp2) = gearmap(cp1, cp2) + 1
        gearval(cp1, cp2) = gearval(cp1, cp2) * gear_parts(i1, 0)
    end do
    do i1=1,found_gears
        cp1 = gear_parts(i1, 1)
        cp2 = gear_parts(i1, 2)
        if (gearmap(cp1, cp2) .eq. 2) then
            gearmap(cp1, cp2) = -1
            gear_ratio_sum = gear_ratio_sum + gearval(cp1, cp2)
        end if
    end do
    print *, "Gear ratio sum: ", gear_ratio_sum



    deallocate(gearmap)
    deallocate(gearval)

end program day3