--[[
    the main user interface for memoire
]]

local Prompt = dofile "prompt.lua"
local recrw = dofile "recrw.lua"
local review = dofile "review.lua"

--[[
    load a deck (a table of tables of `Prompt`s) from a Recfile
]]
local function loaddeck(fname)
    local fh = io.open(fname)
    if not fh then return nil end
    local rt = fh:read "a"
    if not rt then return nil end
    fh:close()
    local pr = recrw.read(rt)
    if not pr then return nil end
    local ep = Prompt:fromrecs(pr)
    return ep
end

--[[
    save a deck (a table of tables of `Prompt`s) to a Recfile
]]
local function savedeck(fname, deck)
    local rrf = {}
    for i, cg in ipairs(deck) do
        rrf[i] = Prompt:torec(cg)
    end
    local wot = recrw.write(rrf)
    local fh = io.open(fname, "w")
    if not fh then io.write("couldn't open output\n") end
    local wr, err = fh:write(wot)
    if not wr then io.write("couldn't write to output\n") end
    fh:close()
end

--[[
    checks (returns boolean) if a response-string is affirmative
]]
local function isyes(s)
    local f = s:sub(1, 1):lower()
    return f == "y" or f == "t"
end

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

--[[
    repository file is hardcoded for now;
    TODO: should be controllable by user in the future
]]
local deckfname = "example.rec"

--[[
    do requested action
]]
-- Add card(s)
if action == "a" then
    -- TODO
-- Help
elseif action == "h" then
    io.write(string.format(
        "Usage: %s ACTION\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 = loaddeck(deckfname)
    -- review each card that needs it
    for i, cg in ipairs(deck) do
        for j, pr in ipairs(cg) do
            if review.should(pr) then
                local st = os.time()
                io.write(string.format(
                    "%s\n",
                    pr.text:gsub("%%A", "___")
                ))
                io.read("l")
                io.write(string.format(
                    "%s\nDid you get it? ",
                    pr.text:gsub("%%A", pr.ans)
                ))
                local resp = io.read("l")
                review.update(pr, st, isyes(resp))
                clear()
            end
        end
    end
    savedeck(deckfname, deck)
-- Statistics
elseif action == "s" then
    -- TODO
else
    io.write "unreachable"
end