//! `GroupFilesService` — the §11.6 shared group-collection FILES contract.
//!
//! The cross-app-sharing counterpart to [`crate::FilesService`], analogous to
//! [`crate::GroupKvService`] / [`crate::GroupDocsService`]. A script reaches it
//! via the explicit `files::shared_collection("name")` handle. The owner of the
//! data is not `cx.app_id`: the impl resolves the **owning group** by walking the
//! calling app's ancestor chain for the nearest group that declares the
//! collection shared with `kind='files'`. That ancestry walk is the isolation
//! boundary — the trait surface takes **no** group id (owner derivation stays in
//! the impl).
//!
//! Trust model (§11.6): **reads are open** to any subtree script (anonymous
//! public HTTP included); **writes require an authenticated principal** with
//! editor+ on the owning group. Same shape as group KV/docs.

use async_trait::async_trait;
use thiserror::Error;
use uuid::Uuid;

use crate::{FileMeta, FileUpdate, FilesListPage, NewFile, SdkCallCx};

#[async_trait]
pub trait GroupFilesService: Send + Sync {
    async fn create(
        &self,
        cx: &SdkCallCx,
        collection: &str,
        new: NewFile,
    ) -> Result<Uuid, GroupFilesError>;

    async fn head(
        &self,
        cx: &SdkCallCx,
        collection: &str,
        id: &str,
    ) -> Result<Option<FileMeta>, GroupFilesError>;

    async fn get(
        &self,
        cx: &SdkCallCx,
        collection: &str,
        id: &str,
    ) -> Result<Option<Vec<u8>>, GroupFilesError>;

    async fn update(
        &self,
        cx: &SdkCallCx,
        collection: &str,
        id: &str,
        upd: FileUpdate,
    ) -> Result<(), GroupFilesError>;

    async fn delete(
        &self,
        cx: &SdkCallCx,
        collection: &str,
        id: &str,
    ) -> Result<bool, GroupFilesError>;

    async fn list(
        &self,
        cx: &SdkCallCx,
        collection: &str,
        cursor: Option<&str>,
        limit: u32,
    ) -> Result<FilesListPage, GroupFilesError>;
}

/// Stub for test bundles that don't exercise shared files collections.
#[derive(Debug, Default, Clone, Copy)]
pub struct NoopGroupFilesService;

#[async_trait]
impl GroupFilesService for NoopGroupFilesService {
    async fn create(
        &self,
        _cx: &SdkCallCx,
        _collection: &str,
        _new: NewFile,
    ) -> Result<Uuid, GroupFilesError> {
        Err(GroupFilesError::Backend(
            "group files is not wired in".into(),
        ))
    }

    async fn head(
        &self,
        _cx: &SdkCallCx,
        _collection: &str,
        _id: &str,
    ) -> Result<Option<FileMeta>, GroupFilesError> {
        Err(GroupFilesError::Backend(
            "group files is not wired in".into(),
        ))
    }

    async fn get(
        &self,
        _cx: &SdkCallCx,
        _collection: &str,
        _id: &str,
    ) -> Result<Option<Vec<u8>>, GroupFilesError> {
        Err(GroupFilesError::Backend(
            "group files is not wired in".into(),
        ))
    }

    async fn update(
        &self,
        _cx: &SdkCallCx,
        _collection: &str,
        _id: &str,
        _upd: FileUpdate,
    ) -> Result<(), GroupFilesError> {
        Err(GroupFilesError::Backend(
            "group files is not wired in".into(),
        ))
    }

    async fn delete(
        &self,
        _cx: &SdkCallCx,
        _collection: &str,
        _id: &str,
    ) -> Result<bool, GroupFilesError> {
        Err(GroupFilesError::Backend(
            "group files is not wired in".into(),
        ))
    }

    async fn list(
        &self,
        _cx: &SdkCallCx,
        _collection: &str,
        _cursor: Option<&str>,
        _limit: u32,
    ) -> Result<FilesListPage, GroupFilesError> {
        Err(GroupFilesError::Backend(
            "group files is not wired in".into(),
        ))
    }
}

/// Failure modes surfaced to the Rhai bridge. Mirrors [`crate::FilesError`] plus
/// the §11.6 `CollectionNotShared` boundary.
#[derive(Debug, Error)]
pub enum GroupFilesError {
    #[error("invalid collection name: {0}")]
    InvalidCollection(String),

    /// No group on the calling app's ancestor chain declares this collection
    /// shared with `kind='files'` — the structural "not shared with you"
    /// boundary (also the outcome for a foreign app).
    #[error("collection {0:?} is not a shared group files collection for this app")]
    CollectionNotShared(String),

    #[error("missing required field: {0}")]
    MissingField(&'static str),

    #[error("file too large: {size} bytes exceeds limit of {limit} bytes")]
    TooLarge { size: usize, limit: usize },

    /// The owning group's shared-files store is at its total-bytes quota
    /// (`PICLOUD_GROUP_FILES_MAX_TOTAL_BYTES`); the write is rejected.
    #[error("group files: quota exceeded ({actual} bytes; limit {limit})")]
    QuotaExceeded { limit: u64, actual: u64 },

    #[error("file name too long: {0} bytes exceeds 255")]
    NameTooLong(usize),

    #[error("content_type too long: {0} bytes exceeds 127")]
    ContentTypeTooLong(usize),

    #[error("file not found")]
    NotFound,

    #[error("file content corrupted (checksum mismatch)")]
    Corrupted,

    /// For reads this is only raised when `cx.principal.is_some()`; for WRITES
    /// it is also raised when the principal is absent (writes fail closed).
    #[error("forbidden")]
    Forbidden,

    #[error("group files backend error: {0}")]
    Backend(String),
}

/// Map the shared [`crate::FilesError`] — returned by `validate_collection`
/// (re-exported as `validate_files_collection`) and the `NewFile`/`FileUpdate`
/// validators that the group-files service reuses — onto the group error. Lives
/// here (not in manager-core) so the orphan rule is satisfied.
impl From<crate::FilesError> for GroupFilesError {
    fn from(e: crate::FilesError) -> Self {
        use crate::FilesError as F;
        match e {
            F::InvalidCollection(c) => Self::InvalidCollection(c),
            F::MissingField(f) => Self::MissingField(f),
            F::TooLarge { size, limit } => Self::TooLarge { size, limit },
            F::NameTooLong(n) => Self::NameTooLong(n),
            F::ContentTypeTooLong(n) => Self::ContentTypeTooLong(n),
            F::NotFound => Self::NotFound,
            F::Corrupted => Self::Corrupted,
            F::Forbidden => Self::Forbidden,
            F::QuotaExceeded { limit, actual } => Self::QuotaExceeded { limit, actual },
            F::Backend(s) => Self::Backend(s),
        }
    }
}
