mod find_up;

use bytes::Bytes;
use codex_protocol::config_types::WindowsSandboxLevel;
use codex_protocol::config_types::WindowsSandboxProxySettingsMode;
use codex_protocol::models::ManagedFileSystemPermissions;
use codex_protocol::models::PermissionProfile;
use codex_protocol::models::SandboxEnforcement;
use codex_protocol::permissions::FileSystemAccessMode;
use codex_protocol::permissions::FileSystemPath;
use codex_protocol::permissions::FileSystemSandboxEntry;
use codex_protocol::permissions::FileSystemSandboxEntryMissingPathBehavior;
use codex_protocol::permissions::FileSystemSandboxKind;
use codex_protocol::permissions::FileSystemSandboxPolicy;
use codex_protocol::permissions::FileSystemSandboxPolicyContext;
use codex_protocol::permissions::FileSystemSpecialPath;
use codex_protocol::permissions::NetworkSandboxPolicy;
use codex_protocol::protocol::SandboxPolicy;
use codex_utils_path_uri::PathUri;
pub use find_up::FindUpErrorPolicy;
pub use find_up::find_nearest_ancestor_with_markers;
pub use find_up::find_nearest_native_ancestor_with_markers;
use futures::Stream;
use serde::Deserialize;
use serde::Serialize;
use std::future::Future;
use std::io;
use std::num::NonZeroUsize;
use std::path::Path;
use std::pin::Pin;
use std::task::Context;
use std::task::Poll;

/// Maximum chunk size returned by [`ExecutorFileSystem::read_file_stream`].
pub const FILE_READ_CHUNK_SIZE: usize = 1024 * 1024;
/// Maximum accepted directory depth for a filesystem walk.
pub const MAX_WALK_DEPTH: usize = 64;
/// Maximum accepted directory count, including the walk root.
pub const MAX_WALK_DIRECTORIES: usize = 10_000;
/// Maximum accepted number of directory entries to examine.
pub const MAX_WALK_ENTRIES: usize = 50_000;
/// Maximum estimated size of a walk response.
pub const MAX_WALK_RESPONSE_BYTES: usize = 4 * 1024 * 1024;
/// Per-entry or per-error overhead charged to the walk response budget.
pub const WALK_RESPONSE_ITEM_OVERHEAD_BYTES: usize = 64;

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct ReadFileOptions {
    pub follow_symlinks: bool,
}

impl Default for ReadFileOptions {
    fn default() -> Self {
        Self {
            follow_symlinks: true,
        }
    }
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct WriteFileOptions {
    pub follow_symlinks: bool,
}

impl Default for WriteFileOptions {
    fn default() -> Self {
        Self {
            follow_symlinks: true,
        }
    }
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct GetMetadataOptions {
    pub follow_symlinks: bool,
}

impl Default for GetMetadataOptions {
    fn default() -> Self {
        Self {
            follow_symlinks: true,
        }
    }
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct CreateDirectoryOptions {
    pub recursive: bool,
    pub follow_symlinks: bool,
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct RemoveOptions {
    pub recursive: bool,
    pub force: bool,
    pub follow_symlinks: bool,
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct CopyOptions {
    pub recursive: bool,
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct FileMetadata {
    pub is_directory: bool,
    pub is_file: bool,
    pub is_symlink: bool,
    /// Size in bytes.
    pub size: u64,
    pub created_at_ms: i64,
    pub modified_at_ms: i64,
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct ReadDirectoryEntry {
    pub file_name: String,
    pub is_directory: bool,
    pub is_file: bool,
}

/// Bounds for a recursive filesystem walk.
#[derive(Clone, Copy, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
#[serde(rename_all = "camelCase")]
pub struct WalkOptions {
    /// Maximum directory depth below the root that may be traversed.
    pub max_depth: usize,
    /// Maximum number of directories that may be traversed, including the root.
    pub max_directories: usize,
    /// Maximum number of directory entries that may be examined.
    pub max_entries: usize,
    /// Whether directory symlinks should be followed.
    pub follow_directory_symlinks: bool,
    /// Whether directories whose names start with `.` should be returned but not traversed.
    #[serde(default, skip_serializing_if = "std::ops::Not::not")]
    pub prune_hidden_directories: bool,
}

/// Type of a filesystem entry returned by a walk.
#[derive(Clone, Copy, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
#[serde(rename_all = "camelCase")]
pub enum WalkEntryKind {
    Directory,
    File,
}

/// One entry returned by a walk.
#[derive(Clone, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
#[serde(rename_all = "camelCase")]
pub struct WalkEntry {
    pub path: PathUri,
    pub kind: WalkEntryKind,
}

/// A descendant that could not be inspected during a walk.
#[derive(Clone, Debug, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
#[serde(rename_all = "camelCase")]
pub struct WalkError {
    pub path: PathUri,
    pub message: String,
}

/// Entries and recoverable errors collected by a bounded walk.
#[derive(Clone, Debug, Default, Eq, PartialEq, serde::Deserialize, serde::Serialize)]
#[serde(rename_all = "camelCase")]
pub struct WalkOutcome {
    pub entries: Vec<WalkEntry>,
    pub errors: Vec<WalkError>,
    pub truncated: bool,
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum ExecFileSystemPath {
    Path { path: PathUri },
    GlobPattern { pattern: String },
    Special { value: FileSystemSpecialPath },
}

impl From<FileSystemPath> for ExecFileSystemPath {
    fn from(value: FileSystemPath) -> Self {
        match value {
            FileSystemPath::Path { path } => Self::Path { path },
            FileSystemPath::GlobPattern { pattern } => Self::GlobPattern { pattern },
            FileSystemPath::Special { value } => Self::Special { value },
        }
    }
}

impl TryFrom<ExecFileSystemPath> for FileSystemPath {
    type Error = io::Error;

    fn try_from(value: ExecFileSystemPath) -> Result<Self, Self::Error> {
        Ok(match value {
            ExecFileSystemPath::Path { path } => {
                path.to_abs_path()?;
                Self::Path { path }
            }
            ExecFileSystemPath::GlobPattern { pattern } => Self::GlobPattern { pattern },
            ExecFileSystemPath::Special { value } => Self::Special { value },
        })
    }
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
pub struct ExecFileSystemSandboxEntry {
    pub path: ExecFileSystemPath,
    pub access: FileSystemAccessMode,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub missing_path_behavior: Option<FileSystemSandboxEntryMissingPathBehavior>,
}

impl From<FileSystemSandboxEntry> for ExecFileSystemSandboxEntry {
    fn from(value: FileSystemSandboxEntry) -> Self {
        Self {
            path: value.path.into(),
            access: value.access,
            missing_path_behavior: value.missing_path_behavior,
        }
    }
}

impl TryFrom<ExecFileSystemSandboxEntry> for FileSystemSandboxEntry {
    type Error = io::Error;

    fn try_from(value: ExecFileSystemSandboxEntry) -> Result<Self, Self::Error> {
        Ok(Self {
            path: value.path.try_into()?,
            access: value.access,
            missing_path_behavior: value.missing_path_behavior,
        })
    }
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum ExecManagedFileSystemPermissions {
    Restricted {
        entries: Vec<ExecFileSystemSandboxEntry>,
        #[serde(default, skip_serializing_if = "Option::is_none")]
        glob_scan_max_depth: Option<NonZeroUsize>,
    },
    Unrestricted,
}

impl From<ManagedFileSystemPermissions> for ExecManagedFileSystemPermissions {
    fn from(value: ManagedFileSystemPermissions) -> Self {
        match value {
            ManagedFileSystemPermissions::Restricted {
                entries,
                glob_scan_max_depth,
            } => Self::Restricted {
                entries: entries.into_iter().map(Into::into).collect(),
                glob_scan_max_depth,
            },
            ManagedFileSystemPermissions::Unrestricted => Self::Unrestricted,
        }
    }
}

impl TryFrom<ExecManagedFileSystemPermissions> for ManagedFileSystemPermissions {
    type Error = io::Error;

    fn try_from(value: ExecManagedFileSystemPermissions) -> Result<Self, Self::Error> {
        Ok(match value {
            ExecManagedFileSystemPermissions::Restricted {
                entries,
                glob_scan_max_depth,
            } => Self::Restricted {
                entries: entries
                    .into_iter()
                    .map(TryInto::try_into)
                    .collect::<io::Result<_>>()?,
                glob_scan_max_depth,
            },
            ExecManagedFileSystemPermissions::Unrestricted => Self::Unrestricted,
        })
    }
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum ExecPermissionProfile {
    Managed {
        file_system: ExecManagedFileSystemPermissions,
        network: NetworkSandboxPolicy,
    },
    Disabled,
    External {
        network: NetworkSandboxPolicy,
    },
}

impl From<PermissionProfile> for ExecPermissionProfile {
    fn from(value: PermissionProfile) -> Self {
        match value {
            PermissionProfile::Managed {
                file_system,
                network,
            } => Self::Managed {
                file_system: file_system.into(),
                network,
            },
            PermissionProfile::Disabled => Self::Disabled,
            PermissionProfile::External { network } => Self::External { network },
        }
    }
}

impl TryFrom<ExecPermissionProfile> for PermissionProfile {
    type Error = io::Error;

    fn try_from(value: ExecPermissionProfile) -> Result<Self, Self::Error> {
        Ok(match value {
            ExecPermissionProfile::Managed {
                file_system,
                network,
            } => Self::Managed {
                file_system: file_system.try_into()?,
                network,
            },
            ExecPermissionProfile::Disabled => Self::Disabled,
            ExecPermissionProfile::External { network } => Self::External { network },
        })
    }
}

#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub struct FileSystemSandboxContext {
    pub permissions: ExecPermissionProfile,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub cwd: Option<PathUri>,
    #[serde(default, skip_serializing_if = "Vec::is_empty")]
    pub workspace_roots: Vec<PathUri>,
    /// Executor-local user home used to resolve home-relative policy paths.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub user_home_dir: Option<PathUri>,
    /// Executor-local default directories used to resolve `:tmpdir` policy entries.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub temporary_directories: Option<Vec<PathUri>>,
    pub windows_sandbox_level: WindowsSandboxLevel,
    #[serde(default)]
    pub windows_sandbox_private_desktop: bool,
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub windows_sandbox_proxy_settings_mode: Option<WindowsSandboxProxySettingsMode>,
    #[serde(default)]
    pub use_legacy_landlock: bool,
}

impl FileSystemSandboxContext {
    pub fn from_legacy_sandbox_policy(
        sandbox_policy: SandboxPolicy,
        cwd: PathUri,
    ) -> io::Result<Self> {
        // Legacy policy projection materializes native roots, so convert at the receiving-host
        // boundary while retaining the URI in the resulting sandbox context.
        let native_cwd = cwd.to_abs_path()?;
        let file_system_sandbox_policy =
            FileSystemSandboxPolicy::from_legacy_sandbox_policy_for_cwd(
                &sandbox_policy,
                &native_cwd,
            );
        let permissions = PermissionProfile::from_runtime_permissions_with_enforcement(
            SandboxEnforcement::from_legacy_sandbox_policy(&sandbox_policy),
            &file_system_sandbox_policy,
            NetworkSandboxPolicy::from(&sandbox_policy),
        );
        Ok(Self::from_permission_profile_with_cwd(permissions, cwd))
    }

    pub fn from_permission_profile(permissions: PermissionProfile) -> Self {
        Self::from_permissions_and_cwd(permissions, /*cwd*/ None)
    }

    pub fn from_permission_profile_with_cwd(permissions: PermissionProfile, cwd: PathUri) -> Self {
        Self::from_permissions_and_cwd(permissions, Some(cwd))
    }

    fn from_permissions_and_cwd(permissions: PermissionProfile, cwd: Option<PathUri>) -> Self {
        let workspace_roots = cwd.iter().cloned().collect();
        Self {
            permissions: permissions.into(),
            cwd,
            workspace_roots,
            user_home_dir: None,
            temporary_directories: None,
            windows_sandbox_level: WindowsSandboxLevel::Disabled,
            windows_sandbox_private_desktop: false,
            windows_sandbox_proxy_settings_mode: None,
            use_legacy_landlock: false,
        }
    }

    pub fn should_run_in_sandbox(&self) -> bool {
        let Ok(permissions) = PermissionProfile::try_from(self.permissions.clone()) else {
            // A sandbox context for another host must not select the unsandboxed filesystem.
            return true;
        };
        let file_system_policy = permissions.file_system_sandbox_policy();
        matches!(file_system_policy.kind, FileSystemSandboxKind::Restricted)
            && !file_system_policy.has_full_disk_write_access()
    }

    /// Borrows the executor-owned paths needed to interpret filesystem policy entries.
    ///
    /// Returns `None` after the cwd has been omitted from a transport context.
    pub fn policy_context(&self) -> Option<FileSystemSandboxPolicyContext<'_>> {
        Some(FileSystemSandboxPolicyContext {
            cwd: self.cwd.as_ref()?,
            workspace_roots: &self.workspace_roots,
            user_home_dir: self.user_home_dir.as_ref(),
            temporary_directories: self.temporary_directories.as_deref(),
        })
    }

    pub fn has_cwd_dependent_permissions(&self) -> bool {
        match &self.permissions {
            ExecPermissionProfile::Managed {
                file_system: ExecManagedFileSystemPermissions::Restricted { entries, .. },
                ..
            } => entries.iter().any(|entry| match &entry.path {
                ExecFileSystemPath::GlobPattern { pattern } => !Path::new(pattern).is_absolute(),
                ExecFileSystemPath::Special {
                    value: FileSystemSpecialPath::ProjectRoots { .. },
                } => true,
                ExecFileSystemPath::Path { .. } | ExecFileSystemPath::Special { .. } => false,
            }),
            ExecPermissionProfile::Managed {
                file_system: ExecManagedFileSystemPermissions::Unrestricted,
                ..
            }
            | ExecPermissionProfile::Disabled
            | ExecPermissionProfile::External { .. } => false,
        }
    }

    pub fn drop_cwd_if_unused(mut self) -> Self {
        if !self.has_cwd_dependent_permissions() {
            self.cwd = None;
            self.workspace_roots.clear();
        }
        self
    }
}

pub type FileSystemResult<T> = io::Result<T>;

/// Future returned by [`ExecutorFileSystem`] operations.
pub type ExecutorFileSystemFuture<'a, T> =
    Pin<Box<dyn Future<Output = FileSystemResult<T>> + Send + 'a>>;

/// Stream of immutable chunks read from an [`ExecutorFileSystem`].
pub struct FileSystemReadStream {
    inner: Pin<Box<dyn Stream<Item = FileSystemResult<Bytes>> + Send + 'static>>,
}

impl FileSystemReadStream {
    /// Wraps a filesystem byte stream.
    pub fn new(stream: impl Stream<Item = FileSystemResult<Bytes>> + Send + 'static) -> Self {
        Self {
            inner: Box::pin(stream),
        }
    }
}

impl Stream for FileSystemReadStream {
    type Item = FileSystemResult<Bytes>;

    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        self.inner.as_mut().poll_next(cx)
    }
}

/// Abstract filesystem access used by components that may operate locally or via
/// a remote environment.
pub trait ExecutorFileSystem: Send + Sync {
    /// Resolves a path within this filesystem.
    fn canonicalize<'a>(
        &'a self,
        path: &'a PathUri,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, PathUri>;

    fn read_file<'a>(
        &'a self,
        path: &'a PathUri,
        options: ReadFileOptions,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, Vec<u8>>;

    /// Reads a file as a stream of chunks no larger than [`FILE_READ_CHUNK_SIZE`].
    fn read_file_stream<'a>(
        &'a self,
        path: &'a PathUri,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, FileSystemReadStream>;

    /// Reads a file and decodes it as UTF-8 text.
    fn read_file_text<'a>(
        &'a self,
        path: &'a PathUri,
        options: ReadFileOptions,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, String> {
        Box::pin(async move {
            let bytes = self.read_file(path, options, sandbox).await?;
            String::from_utf8(bytes).map_err(|err| io::Error::new(io::ErrorKind::InvalidData, err))
        })
    }

    fn write_file<'a>(
        &'a self,
        path: &'a PathUri,
        contents: Vec<u8>,
        options: WriteFileOptions,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, ()>;

    fn create_directory<'a>(
        &'a self,
        path: &'a PathUri,
        create_directory_options: CreateDirectoryOptions,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, ()>;

    fn get_metadata<'a>(
        &'a self,
        path: &'a PathUri,
        options: GetMetadataOptions,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, FileMetadata>;

    fn read_directory<'a>(
        &'a self,
        path: &'a PathUri,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, Vec<ReadDirectoryEntry>>;

    /// Recursively lists descendants, optionally following directory symlinks.
    fn walk<'a>(
        &'a self,
        path: &'a PathUri,
        options: WalkOptions,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, WalkOutcome>;

    fn remove<'a>(
        &'a self,
        path: &'a PathUri,
        remove_options: RemoveOptions,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, ()>;

    fn copy<'a>(
        &'a self,
        source_path: &'a PathUri,
        destination_path: &'a PathUri,
        copy_options: CopyOptions,
        sandbox: Option<&'a FileSystemSandboxContext>,
    ) -> ExecutorFileSystemFuture<'a, ()>;
}