#!/usr/bin/env lua
--[[
    the main user interface for memoire
]]

local SRC_DIR = arg[0]:match("^.*/") or ""

local Prompt = dofile(SRC_DIR .. "prompt.lua")
local review = dofile(SRC_DIR .. "review.lua")
local loader = dofile(SRC_DIR .. "loader.lua")

--[[
    gets the score (again/hard/good/easy/correction) from a string by first character
    scores are numbers, higher is easier, -1 is correction
]]
local function succfromstr(s)
    local f = s:sub(1, 1):lower()
    if f == "0" or f == "a" then
        return 0
    elseif f == "1" or f == "h" then
        return 0.5
    elseif f == "2" or f == "g" then
        return 1
    elseif f == "3" or f == "e" then
        return 1.5
    elseif f == "-" or f == "c" then
        return -1
    end
    return 1
end

--[[
    clears the terminal
    implementation may be platform-specific
]]
local function clear()
    -- XTerm
    io.write("\x1bc")
end

--[[
    display text with images, inserted with `IMG[path]`
    implementation may be platform-specific
    `basepath` points to the base directory of the images
]]
local function imgify(text, basepath)
    -- adapted from https://stackoverflow.com/a/1579673
    local PATTERN = "(.-)IMG%[([^%]]+)%]"
    -- Cygwin/Mintty
    local DISPIMG = function(path)
        if path and #path > 0 then
            io.write("\n")
            os.execute(string.format("imgcat %s%s", basepath, path))
        end
    end
    local le = 1
    local s, e, pt, ip = text:find(PATTERN)
    while s do
        io.write(pt)
        DISPIMG(ip)
        le = e + 1
        s, e, pt, ip = text:find(PATTERN, le)
        io.write(pt or "")
        DISPIMG(ip)
    end
    if le <= #text then
        io.write(text:sub(le))
    end
end

--[[
    rounds `x` to `n` places (default 0) after the radix point
    in base `b` (default 10)
]]
local function round(x, n, b)
    local b = b or 10
    local n = n or 0
    if n == 0 then
        return math.tointeger(math.floor(x * b ^ n) / b ^ n)
    else
        return math.floor(x * b ^ n) / b ^ n
    end
end

--[[
    return human-friendly string to present a duration (input in seconds),
    e.g. "44:37", "4.8h", "11d", "8.3m", "17.4y"
]]
local function disptime(ts)
    local YDAY = 365.24
    local MDAY = YDAY / 12
    local DSEC = 86400
    local HSEC = 3600
    if ts >= 3 * YDAY * DSEC then
        return round(ts / (YDAY * DSEC), 1) .. "y"
    elseif ts >= 4 * MDAY * DSEC then
        return round(ts / (MDAY * DSEC), 1) .. "m"
    elseif ts >= 10 * DSEC then
        return round(ts / DSEC) .. "d"
    elseif ts >= 1.5 * DSEC then
        return round(ts / DSEC, 1) .. "d"
    elseif ts >= 8 * HSEC then
        return round(ts / HSEC) .. "h"
    elseif ts >= HSEC then
        return round(ts / HSEC, 1) .. "h"
    else
        return string.format("%d:%02d", round(ts / 60), round(ts % 60))
    end
end

--[[
    check action based on first command-line argument;
    if nothing valid given, default to help
]]
local action = nil
if arg[1] then
    local fc = arg[1]:sub(1, 1)
    if fc == "a" or fc == "h" or fc == "r" or fc == "s" then
        action = fc
    else
        action = "h"
    end
else
    action = "h"
end

local deckfname = "example.rec"
if arg[2] then
    deckfname = arg[2]
end

math.randomseed(os.time())

--[[
    do requested action
]]
-- Add card(s)
if action == "a" then
    local deck = loader.load(deckfname)
    if deck then
        io.write("Reading prompts -- press Ctrl-D to stop\n")
        local rt = io.read("a")
        local cardctr = 0
        local prctr = 0
        for pt in rt:gmatch("(..-)\n\n") do
            local nc = {}
            -- these Prompts will just be converted to Rec, so we don't need to exclude answers from prompt-text
            for _re in pt:gmatch("%{[^%}]+%}") do
                table.insert(nc, Prompt:new(pt, "", os.time(), 30, 0, 0, os.time()))
                prctr = prctr + 1
            end
            table.insert(deck, nc)
            cardctr = cardctr + 1
        end
        io.write(string.format(
            "Added %d cards (%d prompts)\n",
            cardctr,
            prctr
        ))
        if cardctr > 0 then
            loader.save(deckfname, deck)
        end
    else
        io.write("Failed to load deck\n")
    end
-- Help
elseif action == "h" then
    io.write(string.format(
        "Usage: %s ACTION [REPO]\n\nACTION may be one of\n    (a)dd card\n    (h)elp\n    (r)eview session\n    (s)tatistics\n",
        arg[0]
    ))
-- Review session
elseif action == "r" then
    local deck = loader.load(deckfname)
    if deck then
        -- collect list of index-pairs for prompts to be reviewed this session
        local ctrt = review.list(deck, function(pr)
            -- exclude prompts that use images or Unicode
            return (not pr.text:find("IMG%[")) and (not pr.text:find("[\u{81}-\u{FFFFF}]"))
        end)
        io.write(string.format(
            "%d prompts are ready for review.\nHow many to review in this session? ", #ctrt
        ))
        local climt = io.read("l")
        local climn = tonumber(climt)
        if climn then
            local editqueue = {}
            local start = os.time()
            -- review prompts in this session's set
            for ind, ip in ipairs(ctrt) do
                if ind > climn then
                    break
                end
                local pr = deck[ip[1]][ip[2]]
                -- remove braces for display
                local pst = pr.text:gsub("%{([^{}]+)%}", "%1")
                local st = os.time()
                imgify(pst:gsub("%%A", "___"), deckfname:match(".*/") or "")
                io.write("\n")
                io.read("l")
                imgify(pst:gsub("%%A", (pr.ans:gsub("%%", "%%%%"))), deckfname:match(".*/") or "")
                io.write(string.format(
                    "\nAgain / Hard (%s) / Good (%s) / Easy (%s) / Correction ",
                    disptime(review.schedule(pr, st, 0.5)),
                    disptime(review.schedule(pr, st, 1)),
                    disptime(review.schedule(pr, st, 1.5))
                ))
                local resp = io.read("l")
                local sc = succfromstr(resp)
                if sc == -1 then
                    table.insert(editqueue, ip[1])
                else
                    review.update(deck[ip[1]][ip[2]], st, sc)
                end
                clear()
            end
            if #ctrt > 0 then
                local endt = os.time()
                io.write(string.format(
                    "Reviewed %d prompts in %d seconds\n",
                    math.min(#ctrt, climn),
                    endt - start
                ))
                io.write(string.format(
                    "(%f seconds per card)\n",
                    (endt - start) / math.min(#ctrt, climn)
                ))
            end
            if #editqueue > 0 then
                io.write(string.format(
                    "\n%d cards queued for editing -- press Enter to proceed",
                    #editqueue
                ))
                io.read("l")
                for ind, ci in ipairs(editqueue) do
                    local pr = deck[ci][1]
                    if pr then
                        io.write(string.format(
                            "Card #%d:\n%s\nCancel correction / Delete / Edit ",
                            ci, pr:spt()
                        ))
                        local resp = io.read("l"):sub(1, 1):lower()
                        if resp == "d" then
                            deck[ci][1].deleted = true
                        elseif resp == "e" then
                            io.write("Enter edited version:\n")
                            local ev = io.read("l")
                            local cardrec = Prompt:torec(deck[ci])
                            cardrec.PromptText = { ev }
                            deck[ci] = Prompt:fromrecs({ cardrec })[1]
                        -- assume all other inputs to mean Cancel
                        else
                        end
                    else
                        io.write(string.format("Card #%d is invalid!\n", ci))
                    end
                end
            end
            if climn > 0 then
                loader.save(deckfname, deck)
            end
        else
            io.write("Input not a number -- aborting\n")
        end
    else
        io.write("Failed to load deck\n")
    end
-- Statistics
elseif action == "s" then
    -- TODO
else
    io.write "unreachable"
end