local io = io

local csv = require "csv"
local uuid = require "uuid"

-- Random number generator for uuid()
local posix_uuid = pcall(function()
    uuid.set_rng(uuid.rng.urandom())
end)
if not posix_uuid then rng = uuid.set_rng(uuid.rng.win_ffi()) end

local M = {}  -- Submission module

-- Adapted from lua-núcleo
local function escape_pattern(s)
    local matches = {
        ["^"] = "%^";
        ["$"] = "%$";
        ["("] = "%(";
        [")"] = "%)";
        ["%"] = "%%";
        ["."] = "%.";
        ["["] = "%[";
        ["]"] = "%]";
        ["*"] = "%*";
        ["+"] = "%+";
        ["-"] = "%-";
        ["?"] = "%?";
        ["\0"] = "%z";
    }

    return (s:gsub(".", matches))
end


M.generate_sip = function(path)
    local sub_data = assert(csv.open(path))
    local md = {}
    local prev_ref, prev_k

    -- Collate metadata.
    local i = 1
    for row in sub_data:lines() do
        ref, k, v = table.unpack(row)
        -- nil-out empty cells (they come through as "")
        if ref == "" then ref = nil end
        if k == "" then k = nil end
        if v == "" then v = nil end

        print("Parsing row:", ref, k, v)
        -- v can be a legit false value.
        if ref and not k and v == nil then
            -- This can be a placeholder for ordering purposes.
            md[ref] = md_ref or {}
            goto continue
        elseif v == nil then
            goto continue
        else
            -- If ref or k are missing, reuse the previous one.
            if ref then prev_ref = ref
            else
                if not prev_ref then
                    -- If column 1 is empty, it must have been set in a
                    -- previous row.
                    error(string.format(
                        "Reference in column 1, row %d not found!", i), 2)
                end
                ref = prev_ref
            end

            if k then prev_k = k
            else
                if not prev_k then
                    -- If column 2 is empty, it must have been set in a
                    -- previous row.
                    error(string.format(
                        "Property key in column 2, row %d not found!", i), 2)
                end
                k = prev_k
            end
        end

        md[ref] = md[ref] or {id = uuid(), path = ref, _sort = i}
        md[ref][k] = md[ref][k] or {}
        if k == "type" then
            md[ref][k] = v
        else
            table.insert(md[ref][k], v)
        end

        ::continue::
        i = i + 1
    end

    -- Move md to an ordered list.
    mdlist = {root_path = path:match("(.*/)")}
    for _, v in pairs(md) do table.insert(mdlist, v) end
    table.sort(mdlist, function (a, b) return (a._sort < b._sort) end)

    -- Infer structure from paths and row ordering.
    for i, v in ipairs(mdlist) do
        for j = i + 1, #mdlist do
            --print(string.format("comparing %s : %s", v.path, mdlist[j].path))
            if not v["next"] and
                    mdlist[j].path:match("(.*/)") == v.path:match("(.*/)") then
                --print("next match.")
                v["next"] = mdlist[j].path
            end
            if not v.firstChild and
                    mdlist[j].path:match("^" .. escape_pattern(v.path)) then
                --print("First child match.")
                v.firstChild = mdlist[j].path
            end
        end
        v._sort = nil
    end

    return mdlist
end


M.deposit = function(sip)
    for i, rsrc in ipairs(sip) do
        print(("Processing resource #%d of %d"):format(i, #sip))
        abs_path = sip.root_path 
    end
end

return M