#!/bin/lua

--[[ Copyright (c) 2026 Alexander Hill

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE. ]]

local posix = require("posix")
local tinytoml = require("tinytoml")

-- TODO: Tie these variables to command line arguments. ~ahill
local config = tinytoml.parse("/etc/maple.toml")
local sysroot = "/"
local templates = "/usr/share/mapleconf"

local function render_template(source, target)
    -- Symbol Reference:
    -- {"literal", string} - Writes `string` to the target
    -- {"value", name} - Writes `config[name]` to the target
    local raw = source:read("*all")
    local result = ""
    local template = {}

    -- Tokenize the given template for easy processing later on ~ahill
    local current = 0
    local last = 0
    local literal = true

    while current do
        current = string.find(raw, "@", current + 1)

        if current then
            if literal then
                table.insert(template, { "literal", string.sub(raw, last + 1, current - 1) })
                literal = false

            else
                if current - last == 1 then
                    table.insert(template, { "literal", "@" })

                else
                    table.insert(template, { "value", string.sub(raw, last + 1, current - 1) })
                end
                literal = true
            end

        else
            table.insert(template, { "literal", string.sub(raw, last + 1) })
        end

        last = current
    end

    for _, v in ipairs(template) do
        if v[1] == "literal" then
            result = result .. v[2]
        elseif v[1] == "value" then
            if config[v[2]] then
                result = result .. config[v[2]]
            else
                print("Unable to locate value \"" .. v[2] .. "\"")
                return
            end
        else
            print("BUG: Symbol type " .. v[1] .. " was not recognized!")
            return
        end
    end

    target:write(result)
end

local function render_directory(stack)
    local path
    if #stack == 0 then
        path = "/"
    else
        path = "/" .. table.concat(stack, "/") .. "/"
    end

    local files = posix.dir(templates .. path)
    for _, entry in ipairs(files) do
        if not string.match(entry, "^%.+$") then
            local fullpath = path .. entry

            local stat = posix.stat(templates .. fullpath)
            if stat.type == "directory" then
                if not posix.access(sysroot .. fullpath) then
                    posix.mkdir(sysroot .. fullpath)
                end

                local newstack = {}
                -- Why does Lua lack the ability to copy tables? ~ahill
                for _, v in ipairs(stack) do
                    table.insert(newstack, v)
                end
                table.insert(newstack, entry)
                render_directory(newstack)

            elseif stat.type == "regular" then
                print("Updating " .. fullpath)

                local template = io.open(templates .. fullpath, "r")
                if template then
                    local target = io.open(sysroot .. fullpath, "w")
                    if target then
                        render_template(template, target)
                        target:close()
                    end
                    template:close()
                end

            else
                print("BUG: Directory entry type " .. stat.type .. " not recognized.")
            end
        end
    end
end

render_directory{}