use crate::VirtualMachineRuntime;
use crate::fs::{FsState, VirtualFS};
use crate::os::{FsFacade, LifecycleFacade, SessionsFacade, VmFacade, WindowFacade};
use crate::process::ProcessManager;
use crate::services::memcard::MemcardService;
use crate::services::window_manager::WindowManager;
use crate::task::TaskManager;
use prometeu_hal::log::{LogEvent, LogLevel, LogService, LogSource};
use prometeu_hal::telemetry::CertificationConfig;
use std::collections::HashMap;
use std::sync::Arc;

pub struct SystemOS {
    pub(super) vm_runtime: VirtualMachineRuntime,
    pub(super) process_manager: ProcessManager,
    pub(super) task_manager: TaskManager,
    pub(super) window_manager: WindowManager,
    pub(super) log_service: LogService,
    pub(super) fs: VirtualFS,
    pub(super) fs_state: FsState,
    pub(super) memcard: MemcardService,
    pub(super) open_files: HashMap<u32, String>,
    pub(super) next_handle: u32,
}

impl SystemOS {
    pub fn new(cap_config: Option<CertificationConfig>) -> Self {
        let log_service = LogService::new(4096);
        let mut os = Self {
            vm_runtime: VirtualMachineRuntime::new_with_log_counter(
                cap_config,
                Arc::clone(&log_service.logs_count),
            ),
            process_manager: ProcessManager::new(),
            task_manager: TaskManager::new(),
            window_manager: WindowManager::new(),
            log_service,
            fs: VirtualFS::new(),
            fs_state: FsState::Unmounted,
            memcard: MemcardService::new(),
            open_files: HashMap::new(),
            next_handle: 1,
        };

        os.log(LogLevel::Info, LogSource::Pos, 0, "PrometeuOS starting...".to_string());

        os
    }

    pub fn log(&mut self, level: LogLevel, source: LogSource, tag: u16, msg: String) {
        self.vm_runtime.log(&mut self.log_service, level, source, tag, msg);
    }

    pub fn trace(&mut self, source: LogSource, msg: String) {
        self.log(LogLevel::Trace, source, 0, msg);
    }

    pub fn trace_tag(&mut self, source: LogSource, tag: u16, msg: String) {
        self.log(LogLevel::Trace, source, tag, msg);
    }

    pub fn debug(&mut self, source: LogSource, msg: String) {
        self.log(LogLevel::Debug, source, 0, msg);
    }

    pub fn debug_tag(&mut self, source: LogSource, tag: u16, msg: String) {
        self.log(LogLevel::Debug, source, tag, msg);
    }

    pub fn info(&mut self, source: LogSource, msg: String) {
        self.log(LogLevel::Info, source, 0, msg);
    }

    pub fn info_tag(&mut self, source: LogSource, tag: u16, msg: String) {
        self.log(LogLevel::Info, source, tag, msg);
    }

    pub fn warn(&mut self, source: LogSource, msg: String) {
        self.log(LogLevel::Warn, source, 0, msg);
    }

    pub fn warn_tag(&mut self, source: LogSource, tag: u16, msg: String) {
        self.log(LogLevel::Warn, source, tag, msg);
    }

    pub fn error(&mut self, source: LogSource, msg: String) {
        self.log(LogLevel::Error, source, 0, msg);
    }

    pub fn error_tag(&mut self, source: LogSource, tag: u16, msg: String) {
        self.log(LogLevel::Error, source, tag, msg);
    }

    pub fn recent_logs(&self, n: usize) -> Vec<LogEvent> {
        self.log_service.get_recent(n)
    }

    pub fn logs_after(&self, seq: u64) -> Vec<LogEvent> {
        self.log_service.get_after(seq)
    }

    pub fn lifecycle(&mut self) -> LifecycleFacade<'_> {
        LifecycleFacade { os: self }
    }

    pub fn sessions(&mut self) -> SessionsFacade<'_> {
        SessionsFacade { os: self }
    }

    pub fn vm(&mut self) -> VmFacade<'_> {
        VmFacade { os: self }
    }

    pub fn fs(&mut self) -> FsFacade<'_> {
        FsFacade { os: self }
    }

    pub fn window(&mut self) -> WindowFacade<'_> {
        WindowFacade { os: self }
    }

    pub(super) fn clear_cartridge_service_state(&mut self) {
        self.open_files.clear();
        self.next_handle = 1;
        self.memcard.clear_all_staging();
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::os::{LifecycleError, LifecycleOperation};
    use crate::process::ProcessState;
    use crate::task::{TaskId, TaskState};

    fn process_state_for_task(os: &SystemOS, task_id: TaskId) -> ProcessState {
        let task = os.task_manager.get(task_id).expect("task should exist");
        os.process_manager.get(task.process_id).expect("process should exist").state
    }

    #[test]
    fn set_foreground_task_marks_task_and_process_running() {
        let mut os = SystemOS::new(None);
        let task_id = os.sessions().create_vm_game_task(42, "Sector Crawl");

        os.lifecycle().suspend_task(task_id).expect("suspend should succeed");
        os.lifecycle().set_foreground_task(task_id).expect("foreground should succeed");

        assert_eq!(
            os.task_manager.get(task_id).expect("task should exist").state,
            TaskState::Foreground
        );
        assert_eq!(process_state_for_task(&os, task_id), ProcessState::Running);
    }

    #[test]
    fn suspend_task_marks_task_and_process_suspended() {
        let mut os = SystemOS::new(None);
        let task_id = os.sessions().create_vm_game_task(42, "Sector Crawl");

        os.lifecycle().suspend_task(task_id).expect("suspend should succeed");

        assert_eq!(
            os.task_manager.get(task_id).expect("task should exist").state,
            TaskState::Suspended
        );
        assert_eq!(process_state_for_task(&os, task_id), ProcessState::Suspended);
    }

    #[test]
    fn resume_task_marks_suspended_task_foreground_and_process_running() {
        let mut os = SystemOS::new(None);
        let task_id = os.sessions().create_vm_game_task(42, "Sector Crawl");

        os.lifecycle().suspend_task(task_id).expect("suspend should succeed");
        os.lifecycle().resume_task(task_id).expect("resume should succeed");

        assert_eq!(
            os.task_manager.get(task_id).expect("task should exist").state,
            TaskState::Foreground
        );
        assert_eq!(process_state_for_task(&os, task_id), ProcessState::Running);
    }

    #[test]
    fn close_task_marks_task_closed_and_process_stopped_without_removing_entities() {
        let mut os = SystemOS::new(None);
        let task_id = os.sessions().create_vm_game_task(42, "Sector Crawl");
        let process_id = os.task_manager.get(task_id).expect("task should exist").process_id;

        os.lifecycle().close_task(task_id).expect("close should succeed");

        assert_eq!(
            os.task_manager.get(task_id).expect("task should remain").state,
            TaskState::Closed
        );
        assert_eq!(
            os.process_manager.get(process_id).expect("process should remain").state,
            ProcessState::Stopped
        );
    }

    #[test]
    fn crash_task_marks_task_and_process_crashed() {
        let mut os = SystemOS::new(None);
        let task_id = os.sessions().create_vm_game_task(42, "Sector Crawl");

        os.lifecycle().crash_task(task_id, None).expect("crash should succeed");

        assert_eq!(
            os.task_manager.get(task_id).expect("task should exist").state,
            TaskState::Crashed
        );
        assert_eq!(process_state_for_task(&os, task_id), ProcessState::Crashed);
    }

    #[test]
    fn lifecycle_operation_missing_task_returns_typed_error() {
        let mut os = SystemOS::new(None);

        assert_eq!(
            os.lifecycle().suspend_task(TaskId(999)),
            Err(LifecycleError::TaskNotFound(TaskId(999)))
        );
    }

    #[test]
    fn lifecycle_operation_missing_process_returns_typed_error() {
        let mut os = SystemOS::new(None);
        let task_id = os.sessions().create_vm_game_task(42, "Sector Crawl");
        let process_id = os.task_manager.get(task_id).expect("task should exist").process_id;

        os.process_manager.mark_stopped(process_id);
        os.process_manager.remove_stopped();

        assert_eq!(
            os.lifecycle().suspend_task(task_id),
            Err(LifecycleError::ProcessNotFound(process_id))
        );
    }

    #[test]
    fn resume_task_from_non_suspended_state_returns_invalid_transition() {
        let mut os = SystemOS::new(None);
        let task_id = os.sessions().create_vm_game_task(42, "Sector Crawl");

        assert_eq!(
            os.lifecycle().resume_task(task_id),
            Err(LifecycleError::InvalidTransition {
                task_id,
                from: TaskState::Foreground,
                operation: LifecycleOperation::Resume,
            })
        );
    }
}