-- furt-lua/src/main.lua
-- Pure Lua HTTP-Server for Furt API-Gateway
-- Dragons@Work Digital Sovereignty Project

local socket = require("socket")
local cjson = require("cjson")

-- Load configuration
local config = require("config.server")

-- HTTP-Server Module
local FurtServer = {}

function FurtServer:new()
    local instance = {
        server = nil,
        port = config.port or 8080,
        host = config.host or "127.0.0.1",
        routes = {}
    }
    setmetatable(instance, self)
    self.__index = self
    return instance
end

-- Add route handler
function FurtServer:add_route(method, path, handler)
    if not self.routes[method] then
        self.routes[method] = {}
    end
    self.routes[method][path] = handler
end

-- Parse HTTP request
function FurtServer:parse_request(client)
    local request_line = client:receive()
    if not request_line then
        return nil
    end
    
    -- Parse request line: "POST /v1/mail/send HTTP/1.1"
    local method, path, protocol = request_line:match("(%w+) (%S+) (%S+)")
    if not method then
        return nil
    end
    
    -- Parse headers
    local headers = {}
    local content_length = 0
    
    while true do
        local line = client:receive()
        if not line or line == "" then
            break
        end
        
        local key, value = line:match("([^:]+): (.+)")
        if key and value then
            headers[key:lower()] = value
            if key:lower() == "content-length" then
                content_length = tonumber(value) or 0
            end
        end
    end
    
    -- Parse body
    local body = ""
    if content_length > 0 then
        body = client:receive(content_length)
    end
    
    return {
        method = method,
        path = path,
        protocol = protocol,
        headers = headers,
        body = body,
        content_length = content_length
    }
end

-- Create HTTP response
function FurtServer:create_response(status, data, content_type)
    content_type = content_type or "application/json"
    local body = ""
    
    if type(data) == "table" then
        body = cjson.encode(data)
    else
        body = tostring(data or "")
    end
    
    local response = string.format(
        "HTTP/1.1 %d %s\r\n" ..
        "Content-Type: %s\r\n" ..
        "Content-Length: %d\r\n" ..
        "Connection: close\r\n" ..
        "Server: Furt-Lua/1.0\r\n" ..
        "\r\n%s",
        status,
        self:get_status_text(status),
        content_type,
        #body,
        body
    )
    
    return response
end

-- Get HTTP status text
function FurtServer:get_status_text(status)
    local status_texts = {
        [200] = "OK",
        [400] = "Bad Request",
        [404] = "Not Found",
        [405] = "Method Not Allowed",
        [500] = "Internal Server Error"
    }
    return status_texts[status] or "Unknown"
end

-- Handle client request
function FurtServer:handle_client(client)
    local request = self:parse_request(client)
    if not request then
        local response = self:create_response(400, {error = "Invalid request"})
        client:send(response)
        return
    end
    
    print(string.format("[%s] %s %s", os.date("%Y-%m-%d %H:%M:%S"), 
          request.method, request.path))
    
    -- Route handling
    local handler = nil
    if self.routes[request.method] and self.routes[request.method][request.path] then
        handler = self.routes[request.method][request.path]
    end
    
    if handler then
        local success, result = pcall(handler, request)
        if success then
            client:send(result)
        else
            print("Handler error: " .. tostring(result))
            local error_response = self:create_response(500, {error = "Internal server error"})
            client:send(error_response)
        end
    else
        local response = self:create_response(404, {error = "Route not found"})
        client:send(response)
    end
end

-- Start HTTP server
function FurtServer:start()
    self.server = socket.bind(self.host, self.port)
    if not self.server then
        error("Failed to bind to " .. self.host .. ":" .. self.port)
    end
    
    print(string.format("Furt HTTP-Server started on %s:%d", self.host, self.port))
    print("Press Ctrl+C to stop")
    
    while true do
        local client = self.server:accept()
        if client then
            client:settimeout(10) -- 10 second timeout
            self:handle_client(client)
            client:close()
        end
    end
end

-- Initialize server and routes
local server = FurtServer:new()

-- Health check route
server:add_route("GET", "/health", function(request)
    local response_data = {
        status = "healthy",
        service = "furt-lua",
        version = "1.0.0",
        timestamp = os.time()
    }
    return server:create_response(200, response_data)
end)

-- Test route for development
server:add_route("POST", "/test", function(request)
    local response_data = {
        message = "Test endpoint working",
        received_data = request.body,
        headers_count = 0
    }
    
    -- Count headers
    for _ in pairs(request.headers) do
        response_data.headers_count = response_data.headers_count + 1
    end
    
    return server:create_response(200, response_data)
end)

-- Mail service route (placeholder for Week 1)
server:add_route("POST", "/v1/mail/send", function(request)
    -- Basic validation
    if not request.body or request.body == "" then
        return server:create_response(400, {error = "No request body"})
    end
    
    -- Try to parse JSON
    local success, data = pcall(cjson.decode, request.body)
    if not success then
        return server:create_response(400, {error = "Invalid JSON"})
    end
    
    -- Basic field validation
    if not data.name or not data.email or not data.message then
        return server:create_response(400, {
            error = "Missing required fields",
            required = {"name", "email", "message"}
        })
    end
    
    -- TODO: Implement actual mail sending via SMTP
    print("Mail request received: " .. data.name .. " <" .. data.email .. ">")
    
    local response_data = {
        success = true,
        message = "Mail queued for sending",
        request_id = os.time() .. "-" .. math.random(1000, 9999)
    }
    
    return server:create_response(200, response_data)
end)

-- Start server
server:start()