# L-10 MCS 507 Wed 13 Sep 2023 : polyrootscall.jl

# This script illustrates calling an external program,
# via input and output text files.
# In this simulation, the external program is julia polyroots.jl.

import Printf

"""
    function make_input(dim::Int,
                        name::String="input.txt")

Generates a random coefficient vector, of dimension dim,
writes the coefficients to file.
By default, the name of the file is input.txt.
"""
function make_input(dim::Int,
                    name::String="input.txt")
    c = rand(dim, 1)
    infile = open(name, "w")
    strn = Printf.@sprintf("%d", length(c)-1)
    write(infile, strn)
    write(infile, "\n")
    for i=1:length(c)
        strc = Printf.@sprintf("%.16e", c[i])
        write(infile, strc)
        write(infile, "\n")
    end
    close(infile)
end

"""
    function get_output(name::String="output.txt")

Opens the file with the given name
and returns the numbers on the file.
"""
function get_output(name::String="output.txt")
    result = []
    infile = open(name, "r")
    lines = readlines(infile)
    for i=1:length(lines)
        nbr = parse(Complex{Float64}, lines[i])
        append!(result, nbr)
    end
    return result
end

"""
    function main()

Generates a random coefficient vector,
writes the coefficients to file,
calls the root finder, and then
reads the roots from file.
"""
function main()
    make_input(5)
    infile = "input.txt"
    run(pipeline(`cat input.txt`, 
        pipeline(`julia polyroots.jl`, stdout="output.txt")))
    #callcmd = `julia polyroots.jl <' input.txt '>' output.txt`
    #run(callcmd)
    r = get_output()
    println("the roots : ")
    for i=1:length(r)
        println(r[i])
    end
end

main()