local nano = require "kong.plugins.open-appsec-waf-kong-plugin.nano_ffi"
local kong = kong

local NanoHandler = {}

NanoHandler.PRIORITY = 3000
NanoHandler.VERSION = "1.0.0"

NanoHandler.sessions = {}
NanoHandler.processed_requests = {} -- Track processed requests

-- **Handles worker initialization**
function NanoHandler.init_worker()
    nano.init_attachment()
end

-- **Handles Request Headers (DecodeHeaders Equivalent)**
function NanoHandler.access(conf)
    local headers = kong.request.get_headers()
    local session_id = nano.generate_session_id()
    kong.service.request.set_header("x-session-id", tostring(session_id))

    if NanoHandler.processed_requests[session_id] then
        kong.ctx.plugin.blocked = true
        return
    end

    local session_data = nano.init_session(session_id)
    if not session_data then
        kong.log.err("Failed to initialize session")
        kong.ctx.plugin.blocked = true
        return kong.response.exit(500, { message = "Session Initialization Failed" })
    end

    kong.ctx.plugin.session_data = session_data
    kong.ctx.plugin.session_id = session_id

    local meta_data = nano.handle_start_transaction()
    local req_headers = nano.handleHeaders(headers)

    local has_content_length = tonumber(ngx.var.http_content_length) and tonumber(ngx.var.http_content_length) > 0
    local contains_body = has_content_length and 1 or 0

    local verdict, response = nano.send_data(session_id, session_data, meta_data, req_headers, contains_body, nano.HttpChunkType.HTTP_REQUEST_FILTER)
    if verdict == nano.AttachmentVerdict.DROP then
        nano.fini_session(session_data)
        kong.ctx.plugin.blocked = true
        return nano.handle_custom_response(session_data, response)
    end

    if contains_body == 1 then
        local body = kong.request.get_raw_body()
        if body and #body > 0 then
            verdict, response = nano.send_body(session_id, session_data, body, nano.HttpChunkType.HTTP_REQUEST_BODY)
            if verdict == nano.AttachmentVerdict.DROP then
                nano.fini_session(session_data)
                kong.ctx.plugin.blocked = true
                return nano.handle_custom_response(session_data, response)
            end
        end

        local ok, verdict, response  = pcall(function()
            return nano.end_inspection(session_id, session_data, nano.HttpChunkType.HTTP_REQUEST_END)
        end)

        if not ok then
            kong.log.err("Error ending request inspection: ", verdict)
            nano.fini_session(session_data)
            kong.ctx.plugin.blocked = true
            return kong.response.exit(500, { message = "Error completing request processing" })
        end


        if verdict == nano.AttachmentVerdict.DROP then
            nano.fini_session(session_data)
            kong.ctx.plugin.blocked = true
            return nano.handle_custom_response(session_data, response)
        end
    else
        verdict, response = nano.end_inspection(session_id, session_data, nano.HttpChunkType.HTTP_REQUEST_END)
        if verdict == nano.AttachmentVerdict.DROP then
            nano.fini_session(session_data)
            kong.ctx.plugin.blocked = true
            return nano.handle_custom_response(session_data, response)
        end
    end

    NanoHandler.processed_requests[session_id] = true
end

function NanoHandler.header_filter(conf)
    local ctx = kong.ctx.plugin
    if ctx.blocked then
        return
    end

    local session_id = ctx.session_id
    local session_data = ctx.session_data

    if not session_id or not session_data then
        kong.log.err("No session data found in header_filter")
        return
    end

    local headers = kong.response.get_headers()
    local header_data = nano.handleHeaders(headers)
    local status_code = kong.response.get_status()
    local content_length = tonumber(headers["content-length"]) or 0

    local verdict, response = nano.send_response_headers(session_id, session_data, header_data, status_code, content_length)
    if verdict == nano.AttachmentVerdict.DROP then
        kong.ctx.plugin.blocked = true
        nano.fini_session(session_data)
        return nano.handle_custom_response(session_data, response)
    end

    ctx.expect_body = not (status_code == 204 or status_code == 304 or (100 <= status_code and status_code < 200) or content_length == 0)
end

function NanoHandler.body_filter(conf)
    local ctx = kong.ctx.plugin
    if ctx.blocked then
        return
    end

    local session_id = ctx.session_id
    local session_data = ctx.session_data

    if not session_id or not session_data or ctx.session_finalized then
        return
    end

    local body = kong.response.get_raw_body()

    if body then
        ctx.body_seen = true
        local verdict, response, modifications = nano.send_body(session_id, session_data, body, nano.HttpChunkType.HTTP_RESPONSE_BODY)

        -- Initialize if not exists
        ctx.body_buffer_chunk = ctx.body_buffer_chunk or 0

        -- Handle body modifications if any
        if modifications then
            body = nano.handle_body_modifications(body, modifications, ctx.body_buffer_chunk)
            kong.response.set_raw_body(body)
        end

        ctx.body_buffer_chunk = ctx.body_buffer_chunk + 1

        if verdict == nano.AttachmentVerdict.DROP then
            nano.fini_session(session_data)
            ctx.session_finalized = true
            return nano.handle_custom_response(session_data, response)
        end
        return
    end

    if ctx.body_seen or ctx.expect_body == false then
        local verdict, response = nano.end_inspection(session_id, session_data, nano.HttpChunkType.HTTP_RESPONSE_END)
        if verdict == nano.AttachmentVerdict.DROP then
            nano.fini_session(session_data)
            ctx.session_finalized = true
            return nano.handle_custom_response(session_data, response)
        end

        nano.fini_session(session_data)
        ctx.session_finalized = true
    end
end

return NanoHandler