-- https://github.com/APItools/router.lua/blob/master/router.lua
local router = {
    _VERSION = "router.lua v2.1.0",
    _DESCRIPTION = "A simple router for Lua",
    _LICENSE = [[
    MIT LICENSE
    * Copyright (c) 2013 Enrique García Cota
    * Copyright (c) 2013 Raimon Grau
    * Copyright (c) 2015 Lloyd Zhou
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:
    The above copyright notice and this permission notice shall be included
    in all copies or substantial portions of the Software.
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
    OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
    IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
    TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
    SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  ]],
}

local COLON_BYTE = string.byte(":", 1)
local WILDCARD_BYTE = string.byte("*", 1)
local HTTP_METHODS = { "get", "post", "put", "patch", "delete", "trace", "connect", "options", "head" }

local function match_one_path(node, path, f)
    for token in path:gmatch "[^/.]+" do
        if WILDCARD_BYTE == token:byte(1) then
            node["WILDCARD"] = { ["LEAF"] = f, ["TOKEN"] = token:sub(2) }
            return
        end
        if COLON_BYTE == token:byte(1) then -- if match the ":", store the param_name in "TOKEN" array.
            node["TOKEN"] = node["TOKEN"] or {}
            token = token:sub(2)
            node = node["TOKEN"]
        end
        node[token] = node[token] or {}
        node = node[token]
    end
    node["LEAF"] = f
end

local function resolve(path, node, params)
    local _, _, current_token, rest = path:find "([^/]+)(.*)"
    if not current_token then
        return node["LEAF"], params
    end

    if node["WILDCARD"] then
        params[node["WILDCARD"]["TOKEN"]] = current_token .. rest
        return node["WILDCARD"]["LEAF"], params
    end

    if node[current_token] then
        local f, bindings = resolve(rest, node[current_token], params)
        if f then
            return f, bindings
        end
    end

    for param_name, child_node in pairs(node["TOKEN"] or {}) do
        local param_value = params[param_name]
        params[param_name] = current_token or param_value -- store the value in params, resolve tail path

        local f, bindings = resolve(rest, child_node, params)
        if f then
            return f, bindings
        end

        params[param_name] = param_value -- reset the params table.
    end

    return false
end

local function merge(destination, origin, visited)
    if type(origin) ~= "table" then
        return origin
    end
    if visited[origin] then
        return visited[origin]
    end
    if destination == nil then
        destination = {}
    end

    for k, v in pairs(origin) do
        k = merge(nil, k, visited) -- makes a copy of k
        if destination[k] == nil then
            destination[k] = merge(nil, v, visited)
        end
    end

    return destination
end

local function merge_params(...)
    local params_list = { ... }
    local result, visited = {}, {}

    for i = 1, #params_list do
        merge(result, params_list[i], visited)
    end

    return result
end

------------------------------ INSTANCE METHODS ------------------------------------
local Router = {}

function Router:resolve(method, path, ...)
    local node = self._tree[method]
    if not node then
        return nil, ("Unknown method: %s"):format(tostring(method))
    end
    return resolve(path, node, merge_params(...))
end

function Router:execute(method, path, ...)
    local f, params = self:resolve(method, path, ...)
    if not f then
        return nil, ("Could not resolve %s %s - %s"):format(tostring(method), tostring(path), tostring(params))
    end
    return true, f(params)
end

function Router:match(method, path, fun)
    if type(method) == "string" then -- always make the method to table.
        method = { method }
    end

    local parsed_methods = {}
    for k, v in pairs(method) do
        if type(v) == "string" then
            -- convert shorthand methods into longhand
            if parsed_methods[v] == nil then
                parsed_methods[v] = {}
            end
            parsed_methods[v][path] = fun
        else
            -- pass methods already in longhand format onwards
            parsed_methods[k] = v
        end
    end

    for m, routes in pairs(parsed_methods) do
        for p, f in pairs(routes) do
            if not self._tree[m] then
                self._tree[m] = {}
            end
            match_one_path(self._tree[m], p, f)
        end
    end
end

for _, method in ipairs(HTTP_METHODS) do
    Router[method] = function(self, path, f) -- Router.get = function(self, path, f)
        self:match(method:upper(), path, f) --   return self:match('GET', path, f)
    end -- end
end

Router["any"] = function(self, path, f) -- match any method
    for _, method in ipairs(HTTP_METHODS) do
        self:match(method:upper(), path, function(params)
            return f(params, method)
        end)
    end
end

local router_mt = { __index = Router }

------------------------------ PUBLIC INTERFACE ------------------------------------
router.new = function()
    return setmetatable({ _tree = {} }, router_mt)
end

return router
