module args

import flag
import os
import runtime
import sim
import math

// customisable through setting VJOBS
const max_parallel_workers = runtime.nr_jobs()

@[params]
pub struct ParserSettings {
pub:
    sequential    bool
    img           bool
    extra_workers int
}

pub struct SequentialArgs {
pub:
    params   sim.SimParams
    grid     sim.GridSettings
    filename string
}

pub struct ParallelArgs {
    SequentialArgs
pub:
    workers int = max_parallel_workers
}

pub type SimArgs = ParallelArgs | SequentialArgs

pub fn parse_args(config ParserSettings) !SimArgs {
    if config.sequential {
        args := parse_sequential_args()!
        return SimArgs(args)
    } else {
        args := parse_parallel_args(config.extra_workers)!
        return SimArgs(args)
    }
}

fn parse_sequential_args() !SequentialArgs {
    mut fp := flag.new_flag_parser(os.args)
    fp.application('vps')
    fp.version('v0.1.0')
    fp.limit_free_args(0, 0)!
    fp.description('This is a pendulum simulation written in pure V')
    fp.skip_executable()

    // output parameters
    width := fp.int('width', `w`, sim.default_width,
        'width of the image output. Defaults to ${sim.default_width}')
    height := fp.int('height', `h`, sim.default_height,
        'height of the image output. Defaults to ${sim.default_height}')
    filename := fp.string('output', `o`, 'out.ppm', 'name of the image output. Defaults to out.ppm')

    // simulation parameters
    rope_length := fp.float('rope-length', 0, sim.default_rope_length,
        'rope length to use on simulation. Defaults to ${sim.default_rope_length}')
    bearing_mass := fp.float('bearing-mass', 0, sim.default_bearing_mass,
        'bearing mass to use on simulation. Defaults to ${sim.default_bearing_mass}')
    magnet_spacing := fp.float('magnet-spacing', 0, sim.default_magnet_spacing,
        'magnet spacing to use on simulation. Defaults to ${sim.default_magnet_spacing}')
    magnet_height := fp.float('magnet-height', 0, sim.default_magnet_height,
        'magnet height to use on simulation. Defaults to ${sim.default_magnet_height}')
    magnet_strength := fp.float('magnet-strength', 0, sim.default_magnet_strength,
        'magnet strength to use on simulation. Defaults to ${sim.default_magnet_strength}')
    gravity := fp.float('gravity', 0, sim.default_gravity,
        'gravity to use on simulation. Defaults to ${sim.default_gravity}')

    fp.finalize() or {
        println(fp.usage())
        return error('none')
    }

    params := sim.sim_params(
        rope_length:     rope_length
        bearing_mass:    bearing_mass
        magnet_spacing:  magnet_spacing
        magnet_height:   magnet_height
        magnet_strength: magnet_strength
        gravity:         gravity
    )

    grid := sim.new_grid_settings(
        width:  width
        height: height
    )

    args := SequentialArgs{
        params:   params
        filename: filename
        grid:     grid
    }

    sim.log('${args}')

    return args
}

fn parse_parallel_args(extra_workers int) !ParallelArgs {
    mut fp := flag.new_flag_parser(os.args)
    fp.application('vps')
    fp.version('v0.1.0')
    fp.limit_free_args(0, 0)!
    fp.description('This is a pendulum simulation written in pure V')
    fp.skip_executable()

    workers := fp.int('workers', 0, max_parallel_workers,
        'amount of workers to use on simulation. Defaults to ${max_parallel_workers}')

    // output parameters
    width := fp.int('width', `w`, sim.default_width,
        'width of the image output. Defaults to ${sim.default_width}')
    height := fp.int('height', `h`, sim.default_height,
        'height of the image output. Defaults to ${sim.default_height}')
    filename := fp.string('output', `o`, 'out.ppm', 'name of the image output. Defaults to out.ppm')

    // simulation parameters
    rope_length := fp.float('rope-length', 0, sim.default_rope_length,
        'rope length to use on simulation. Defaults to ${sim.default_rope_length}')
    bearing_mass := fp.float('bearing-mass', 0, sim.default_bearing_mass,
        'bearing mass to use on simulation. Defaults to ${sim.default_bearing_mass}')
    magnet_spacing := fp.float('magnet-spacing', 0, sim.default_magnet_spacing,
        'magnet spacing to use on simulation. Defaults to ${sim.default_magnet_spacing}')
    magnet_height := fp.float('magnet-height', 0, sim.default_magnet_height,
        'magnet height to use on simulation. Defaults to ${sim.default_magnet_height}')
    magnet_strength := fp.float('magnet-strength', 0, sim.default_magnet_strength,
        'magnet strength to use on simulation. Defaults to ${sim.default_magnet_strength}')
    gravity := fp.float('gravity', 0, sim.default_gravity,
        'gravity to use on simulation. Defaults to ${sim.default_gravity}')

    fp.finalize() or {
        println(fp.usage())
        return error('none')
    }

    params := sim.sim_params(
        rope_length:     rope_length
        bearing_mass:    bearing_mass
        magnet_spacing:  magnet_spacing
        magnet_height:   magnet_height
        magnet_strength: magnet_strength
        gravity:         gravity
    )

    grid := sim.new_grid_settings(
        width:  width
        height: height
    )

    args := ParallelArgs{
        params:   params
        filename: filename
        grid:     grid
        workers:  get_workers(workers, extra_workers)
    }
    sim.log('${args}')

    return args
}

@[inline]
fn get_workers(workers int, extra_workers int) int {
    return math.max(1, workers + extra_workers)
}