# Useful information:
#
# https://en.wikipedia.org/wiki/List_of_physical_quantities
# https://www.themeasureofthings.com/
#
# "free" Unitful units: efijno r v xzDEIOQUXZ |
# "used" Unitful units: e i   p t w           |
module IIPAU

import Unitful
using Unitful: @unit, @affineunit, @u_str
export item
export @b6_str
export yocte, zepte, atte, femte, pice, nane, micre, mille, cente, dice
export yotte, zette, exe, pete, tere, gige, mege, kile, hecte, dece

export pace, tick, egg


function __init__()
    Unitful.register(IIPAU)
end
#Unitful.register(IIPAU)

# Additional Constants
kₑ = 8987551792u"N*m^2/C^2"
mₑ = 9.109e-31u"kg"
mᵤ = 1.6605390666e-27u"kg"
mₙ = 1.674927498e-27u"kg"
kb = 1.380649e-23u"J/K"
ϵ₀ = 8.854e-12u"F/m"

# Natural Units
@unit lₛ "lₛ" StoneyLength (sqrt(Unitful.G * kₑ * Unitful.q^2 / Unitful.c^4) |> Unitful.upreferred) false
@unit mₛ "mₛ" StoneyMass (sqrt(kₑ * Unitful.q^2 / Unitful.G) |> Unitful.upreferred) false
@unit tₛ "tₛ" StoneyTime (sqrt(Unitful.G * kₑ * Unitful.q^2 / Unitful.c^6) |> Unitful.upreferred) false

@unit lₚ "lₚ" PlanckLength sqrt(Unitful.ħ * Unitful.G / Unitful.c^3) false
@unit mₚ "mₚ" PlanckMass sqrt(Unitful.ħ * Unitful.c / Unitful.G) false
@unit tₚ "tₚ" PlanckTime sqrt(Unitful.ħ * Unitful.G / Unitful.c^5) false
@unit Tₚ "Tₚ" PlanckTemperature sqrt(Unitful.ħ * Unitful.c ^ 5 / (Unitful.G * Unitful.k ^ 2)) false
@unit qₚ "qₚ" Planckcharge sqrt(4π * Unitful.ϵ0 * Unitful.ħ * Unitful.c) false
@unit Qₚ "Qₚ" PlanckCharge sqrt(Unitful.ϵ0 * Unitful.ħ * Unitful.c) false
item = @unit count "count" Count (1 / Unitful.Na) false

# Senary prefixes
function base6(number::AbstractString)
    if occursin('e', number)
        (digits, exponent) = split(number, 'e')
    else
        (digits, exponent) = (number, "0")
    end

    if occursin('.', digits)
        value = parse(BigFloat, digits, base=6)
    else
        value = parse(BigInt, digits, base=6)
    end

    expval = parse(Int, exponent, base=6)

    if expval < 0
        return 1 // (value * BigInt(6) ^ (-expval))
    else
        return value * BigInt(6) ^ expval
    end
end

macro b6_str(digits)
    value = base6(digits)

    return :( $value )
end

yocte = b6"1e-52" # y |
zepte = b6"1e-44" # z |
atte = b6"1e-40" # a  |
femte = b6"1e-32" # f |
pice = b6"1e-24" # p  |
nane = b6"1e-20" # n  |
micre = b6"1e-12" # μ |
mille = b6"1e-4" # m  |
cente = b6"1e-2" # c  |
dice = b6"1e-1" # d   |
dece = b6"1e1" # de   |
hecte = b6"1e2" # h   |
kile = b6"1e4" # k    |
mege = b6"1e12" # M   |
gige = b6"1e20" # G   |
tere = b6"1e24" # T   |
pete = b6"1e32" # P   |
exe = b6"1e40" # E    |
zette = b6"1e44" # Z  |
yotte = b6"1e52" # Y  |

# TODO: consider scaling instants up, using moment for the base unit at a more
# human timescale

# Base Units
pace = 1@unit p "p" Pace (lₛ * b6"1e114") false # ~86cm
tick = 1@unit t "t" Tick (tₛ * b6"3e132") false # ~0.52s = 300₆ instants (1/tick ~115bpm)
egg = 1@unit e "e" Egg (mₛ * b6"1e14") false # ~112g
jolt = 1@unit j "j" Jolt (b6"1e34" * Unitful.q / tick) false # ~40mA painful jolt (https://electronics.stackexchange.com/questions/19103/how-much-voltage-current-is-dangerous)

# Convenience Units
instant = 1@unit i "i" Instant (tₛ * b6"1e130") false # ~5ms (1000₆ instants is about a second)
# TODO: larger chunks of meaningful time (akin to minutes/hours)
# TODO: name ~0.5L which is a mille pace^3?

# Derived Units
walk = 1@unit w "w" Walk (1 * pace / tick) false # ~6km/h (pretty quick walk)
touch = 1@unit ṫ "ṫ" Touch (1 * egg * pace / tick ^ 2) false # ~0.36N (half what it takes to press a key on a keyboard)

#= Useful Constants ============================================================
 Earth's gravitational constant: gₑ ≈ 3₆p/t²
 Speed of light: c ≡ 3e14₆p/t
===============================================================================#

#=
export stride, skip, bed, gulp
export moment, instant, wait
export amble, shot
export ball
export brr
export press, bite, snack
export jolt
export lotta, alotta

# Lengths (root unit: skip)
skip = 1@unit sk "sk" Skip (lₚ * b6"1e112") false               # ~28cm
stride = 1@unit st "st" Stride (dece * skip) false              # ~1.7m
sprint = 1@unit sp "sp" Sprint (kile * skip) false              # ~360m
# Note: a kile stride is about 1 nautical mile

# Areas (root unit: paper)
paper = 1@unit pa "pa" Paper (skip * skip) false                # ~0.08m²
bed = 1@unit bd "bd" Bed (stride * stride) false                # ~2.8m²

# Volumes (root unit: gulp)
gulp = 1@unit gu "gu" Gulp ((dice * IIPAU.skip) ^ 3) false      # ~100 mL

# Durations (root unit: instant)
instant = 1@unit in "in" Instant (tₚ * b6"1e131") false          # ~1/3s
moment = 1@unit mo "mo" Moment (dece * instant)  false           # ~2s
wait = 1@unit w "w" Wait (kile * moment) false                   # ~43.9 minutes

# Speed (root unit: amble)
amble = 1@unit amb "amb" Amble (skip / instant) false           # ~3km/h
shot = 1@unit sh "sh" Shot (kile * amble) false                 # ~1km/s (bullet speed)

# Mass (root unit: ball)
ball = 1@unit bl "bl" Ball (mₚ * b6"1.0e13") false              # ~200g (note: Float to fix Int64 overflow)

# Temperate (root unit: brr, base unit degree of comfort)
brr = 1@unit br "br" Brr (Tₚ * b6"1e-110") false                # ~0.3K
@affineunit °c "°c" (Int(b6"4400") * brr)                       # ~13°C -> 0°c
# This sets up that 0 is uncomfortably cold, 100₆ is comfortable, and 200₆ is
# uncomfortably warm (13, 23.5, 34)°C respectively

# Force (root unit: press)
press = 1@unit pr "pr" Press (ball * skip / instant^2) false    # ~0.5N (key press on keyboard)

# NOTE: 1bi / Mto = 1st, aka a bite is one megatouch stride (or a kileshove stride)
# NOTE: 1sn / Mpr = 1sk, aka a snack is one megepress skip

# Energy (root unit: snack)
snack = 1@unit sn "sn" Snack (b6"1.0e12" * press * skip) false                    # ~60cal
bite = 1@unit bi "bi" Bite (dice * snack) false # ~10cal

# Electricity, based on a common static shock
# ~0-2mJ / ~1-5KV = ~5e-8 to 5e-7C

# Charge (root unit: jolt)
jolt = 1@unit jo "jo" Jolt (b6"1e23" * Unitful.q) false         # ~7.5e-8C (a moderate static shock of charge)

# TODO: Voltage and consider charge in lotta electron charges (q in Unitful
# [leads to about 2e7C, which is a lot, but might make cleaner 'volts'])
# or consider using resistivity or conductivity of something common?
temp = 1@unit tmp "tmp" Temp (jolt / moment) false

# "Count" (root unit: lotta [mole equivalent]) ~1.32e26
lotta = 1@unit lo "lo" Lotta (1u"mol" * 1u"bl" / 1u"g") false   # ~220mol
alotta = (1u"lo" |> item).val                                   # ~1.32e26

function prefer_iipau()
    Unitful.preferunits(u"sk,mo,bl,br,lo,tmp"...)
end

function prefer_natural()
    Unitful.preferunits(u"lₚ,mₚ,tₚ,Tₚ,qₚ,Qₚ,count"...)
end
=#

end # module IIPAU