//! Storage-owned service boundary for the Iced desktop presentation adapter.

use std::{error::Error, fmt, path::Path};

use crate::{
    authentication::{
        AuthenticationTimeout, NativeAuthenticationHandle, NativeAuthenticationSession,
    },
    command::{CopyRequest, FindRequest, GrepRequest, InitRequest, MoveRequest, RemoveRequest},
    config::{Config, ConfigSettings, EditorCommand},
    crypto::{KeyInfo, KeyStore, SecretProvider},
    document::{DocumentError, EntryDocument, EntryDocumentService},
    git::{AutomaticEntryCommitter, AutomaticPolicyCommitter, AutomaticTreeCommitter, GitIdentity},
    mutation::{MutationOutcome, TreeMutator},
    presentation::ClipboardTimeout,
    read::{FindResults, GrepResults, TreeModel, VaultReader},
    recipient::{
        PolicyCommit, PolicyCommitError, PolicyCommitter, RecipientPolicyManager,
        RecipientPolicyOutcome,
    },
    repository::{DirectoryPath, Repository},
    secret_store::SecretProtectionPolicy,
    write::{OverwriteDecision, VaultWriter, WriteError, WriteOutcome},
};

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum DesktopErrorKind {
    Configuration,
    Authentication,
    KeyMaterial,
    Repository,
    Read,
    Document,
    Git,
    Conflict,
    Unchanged,
    MissingDefaultKey,
    EntryExists,
    Mutation,
}

#[derive(Debug)]
pub struct DesktopError {
    kind: DesktopErrorKind,
    message: String,
}

impl DesktopError {
    pub fn kind(&self) -> DesktopErrorKind {
        self.kind
    }

    fn new(kind: DesktopErrorKind, error: impl fmt::Display) -> Self {
        Self {
            kind,
            message: error.to_string(),
        }
    }

    fn document(error: DocumentError) -> Self {
        let kind = match &error {
            DocumentError::Write(WriteError::ConcurrentModification { .. }) => {
                DesktopErrorKind::Conflict
            }
            DocumentError::Write(WriteError::Unchanged) => DesktopErrorKind::Unchanged,
            _ => DesktopErrorKind::Document,
        };
        Self::new(kind, error)
    }
}

impl fmt::Display for DesktopError {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter.write_str(&self.message)
    }
}

impl Error for DesktopError {}

#[derive(Clone, Debug)]
pub struct DesktopStorage {
    config: Config,
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub enum DesktopMutationRequest {
    Remove(RemoveRequest),
    Move(MoveRequest),
    Copy(CopyRequest),
}

impl DesktopMutationRequest {
    pub fn source(&self) -> &str {
        match self {
            Self::Remove(request) => &request.entry,
            Self::Move(request) => &request.source,
            Self::Copy(request) => &request.source,
        }
    }
}

impl DesktopStorage {
    pub fn load(explicit: Option<&Path>) -> Result<Self, DesktopError> {
        Config::load(explicit)
            .map(|config| Self { config })
            .map_err(|error| DesktopError::new(DesktopErrorKind::Configuration, error))
    }

    pub fn system() -> Result<DesktopBootstrap, DesktopError> {
        Self::load(None)?.bootstrap()
    }

    pub fn bootstrap(self) -> Result<DesktopBootstrap, DesktopError> {
        let keys = KeyStore::load(self.config.key_material())
            .map_err(|error| DesktopError::new(DesktopErrorKind::KeyMaterial, error))?;
        let handle = keys
            .resolve(self.config.default_key().as_str())
            .map_err(|error| DesktopError::new(DesktopErrorKind::KeyMaterial, error))?;
        let key = keys
            .infos()
            .find(|key| key.fingerprint() == handle.fingerprint())
            .ok_or_else(|| {
                DesktopError::new(
                    DesktopErrorKind::MissingDefaultKey,
                    "the configured GPG key is unavailable",
                )
            })?;
        let authentication = NativeAuthenticationSession::system(
            SecretProtectionPolicy::default(),
            self.config.authentication_timeout(),
        )
        .map_err(|error| DesktopError::new(DesktopErrorKind::Authentication, error))?;
        Ok(DesktopBootstrap {
            storage: self,
            authentication,
            key,
        })
    }

    pub fn clipboard_timeout(&self) -> ClipboardTimeout {
        self.config.clipboard_timeout()
    }

    pub fn authentication_timeout(&self) -> AuthenticationTimeout {
        self.config.authentication_timeout()
    }

    pub fn vault(&self) -> &Path {
        self.config.vault()
    }

    pub fn config_source(&self) -> &Path {
        self.config.source()
    }

    pub fn default_key(&self) -> &str {
        self.config.default_key().as_str()
    }

    pub fn configured_editor(&self) -> Option<&EditorCommand> {
        self.config.configured_editor()
    }

    pub fn settings(&self) -> ConfigSettings {
        self.config.settings()
    }

    pub fn update_settings(&self, settings: ConfigSettings) -> Result<Self, DesktopError> {
        let storage = self.validate_settings(settings)?;
        storage.persist()?;
        Ok(storage)
    }

    pub fn update_settings_and_bootstrap(
        &self,
        settings: ConfigSettings,
    ) -> Result<DesktopBootstrap, DesktopError> {
        let bootstrap = self.validate_settings(settings)?.bootstrap()?;
        bootstrap.storage.persist()?;
        Ok(bootstrap)
    }

    fn validate_settings(&self, mut settings: ConfigSettings) -> Result<Self, DesktopError> {
        let repository = Repository::open(settings.vault())
            .map_err(|error| DesktopError::new(DesktopErrorKind::Repository, error))?;
        settings.set_vault(repository.root_path().to_owned());
        let config = self
            .config
            .with_settings(settings)
            .map_err(|error| DesktopError::new(DesktopErrorKind::Configuration, error))?;
        let storage = Self { config };
        let keys = storage.keys()?;
        keys.resolve(storage.config.default_key().as_str())
            .map_err(|error| DesktopError::new(DesktopErrorKind::KeyMaterial, error))?;
        storage.tree()?;
        Ok(storage)
    }

    fn persist(&self) -> Result<(), DesktopError> {
        self.config
            .persist()
            .map_err(|error| DesktopError::new(DesktopErrorKind::Configuration, error))
    }

    /// Validate a selected folder through the same repository and key path as
    /// normal desktop reads, then atomically update the shared configuration.
    pub fn switch_vault(&self, vault: &Path) -> Result<Self, DesktopError> {
        let mut settings = self.settings();
        settings.set_vault(vault.to_owned());
        self.update_settings(settings)
    }

    pub fn tree(&self) -> Result<TreeModel, DesktopError> {
        let repository = self.repository()?;
        let keys = self.keys()?;
        VaultReader::new(&repository, &keys)
            .list(&DirectoryPath::root())
            .map_err(|error| DesktopError::new(DesktopErrorKind::Read, error))
    }

    pub fn find(&self, request: &FindRequest) -> Result<FindResults, DesktopError> {
        let repository = self.repository()?;
        let keys = self.keys()?;
        VaultReader::new(&repository, &keys)
            .find(&request.terms)
            .map_err(|error| DesktopError::new(DesktopErrorKind::Read, error))
    }

    pub fn grep_active(
        &self,
        handle: &NativeAuthenticationHandle,
        request: &GrepRequest,
    ) -> Result<GrepResults, DesktopError> {
        handle
            .ensure_active()
            .map_err(|error| DesktopError::new(DesktopErrorKind::Authentication, error))?;
        let mut provider = handle.clone();
        self.grep(request, &mut provider)
    }

    pub fn grep(
        &self,
        request: &GrepRequest,
        provider: &mut impl SecretProvider,
    ) -> Result<GrepResults, DesktopError> {
        let repository = self.repository()?;
        let keys = self.keys()?;
        VaultReader::new(&repository, &keys)
            .grep(request, provider)
            .map_err(|error| DesktopError::new(DesktopErrorKind::Read, error))
    }

    pub fn mutate_active(
        &self,
        handle: &NativeAuthenticationHandle,
        request: &DesktopMutationRequest,
        overwrite: OverwriteDecision,
    ) -> Result<MutationOutcome, DesktopError> {
        handle
            .ensure_active()
            .map_err(|error| DesktopError::new(DesktopErrorKind::Authentication, error))?;
        let mut provider = handle.clone();
        self.mutate(request, overwrite, &mut provider)
    }

    pub fn mutate(
        &self,
        request: &DesktopMutationRequest,
        overwrite: OverwriteDecision,
        provider: &mut impl SecretProvider,
    ) -> Result<MutationOutcome, DesktopError> {
        let repository = self.repository()?;
        let keys = self.keys()?;
        let mut committer = AutomaticTreeCommitter::for_source(
            &repository,
            request.source(),
            GitIdentity::ironstorage(),
        )
        .map_err(|error| DesktopError::new(DesktopErrorKind::Git, error))?;
        let mutator = TreeMutator::new(&repository, &keys);
        match request {
            DesktopMutationRequest::Remove(request) => {
                mutator.remove(request, overwrite, &mut committer)
            }
            DesktopMutationRequest::Move(request) => {
                mutator.move_tree(request, overwrite, None, provider, &mut committer)
            }
            DesktopMutationRequest::Copy(request) => {
                mutator.copy(request, overwrite, None, provider, &mut committer)
            }
        }
        .map_err(|error| DesktopError::new(DesktopErrorKind::Mutation, error))
    }

    /// Enumerate storage-validated encryption keys for recipient selection.
    pub fn key_infos(&self) -> Result<Vec<KeyInfo>, DesktopError> {
        Ok(self.keys()?.infos().filter(KeyInfo::can_encrypt).collect())
    }

    /// Apply an upstream-compatible root or nested `.gpg-id` policy while the
    /// shared authentication lease is active.
    pub fn apply_active_recipient_policy(
        &self,
        handle: &NativeAuthenticationHandle,
        request: &InitRequest,
        default_key: &str,
    ) -> Result<(Self, RecipientPolicyOutcome), DesktopError> {
        handle
            .ensure_active()
            .map_err(|error| DesktopError::new(DesktopErrorKind::Authentication, error))?;
        let mut provider = handle.clone();
        self.apply_recipient_policy(request, default_key, &mut provider)
    }

    pub fn apply_recipient_policy(
        &self,
        request: &InitRequest,
        default_key: &str,
        provider: &mut impl SecretProvider,
    ) -> Result<(Self, RecipientPolicyOutcome), DesktopError> {
        let repository = self.repository()?;
        let keys = self.keys()?;
        let default = keys
            .infos()
            .find(|key| key.fingerprint().as_str() == default_key)
            .ok_or_else(|| {
                DesktopError::new(
                    DesktopErrorKind::MissingDefaultKey,
                    "the selected default GPG key is unavailable",
                )
            })?;
        if !default.has_secret() {
            return Err(DesktopError::new(
                DesktopErrorKind::MissingDefaultKey,
                "the selected default GPG key has no secret key material",
            ));
        }
        let mut settings = self.settings();
        settings.set_default_key(default_key.to_owned());
        let replacement = self.validate_settings(settings)?;
        let directory = request.path.as_deref().unwrap_or_default();
        let committer = AutomaticPolicyCommitter::for_directory(
            &repository,
            directory,
            GitIdentity::ironstorage(),
        )
        .map_err(|error| DesktopError::new(DesktopErrorKind::Git, error))?;
        let mut committer = ConfigPolicyCommitter {
            git: committer,
            previous: &self.config,
            replacement: &replacement.config,
            persisted: false,
        };
        let outcome = RecipientPolicyManager::new(&repository, &keys)
            .apply_init(request, None, provider, &mut committer)
            .map_err(|error| DesktopError::new(DesktopErrorKind::Repository, error))?;
        if !committer.persisted {
            replacement.persist()?;
        }
        Ok((replacement, outcome))
    }

    /// Open a collision-free in-memory draft. No repository bytes are written
    /// until the structured document is explicitly saved.
    pub fn create_active_document(
        &self,
        handle: &NativeAuthenticationHandle,
        entry: &str,
    ) -> Result<EntryDocument, DesktopError> {
        handle
            .ensure_active()
            .map_err(|error| DesktopError::new(DesktopErrorKind::Authentication, error))?;
        let mut provider = handle.clone();
        self.create_document(entry, &mut provider)
    }

    pub fn create_document(
        &self,
        entry: &str,
        provider: &mut impl SecretProvider,
    ) -> Result<EntryDocument, DesktopError> {
        let repository = self.repository()?;
        let keys = self.keys()?;
        if VaultWriter::new(&repository, &keys)
            .entry_exists(entry)
            .map_err(|error| DesktopError::new(DesktopErrorKind::Document, error))?
        {
            return Err(DesktopError::new(
                DesktopErrorKind::EntryExists,
                format!("password-store entry already exists: {entry}"),
            ));
        }
        EntryDocumentService::new(&repository, &keys)
            .open(entry, provider)
            .map_err(DesktopError::document)
    }

    pub fn open_document(
        &self,
        entry: &str,
        secrets: &mut impl SecretProvider,
    ) -> Result<EntryDocument, DesktopError> {
        let repository = self.repository()?;
        let keys = self.keys()?;
        EntryDocumentService::new(&repository, &keys)
            .open(entry, secrets)
            .map_err(DesktopError::document)
    }

    pub fn save_document(&self, document: &EntryDocument) -> Result<WriteOutcome, DesktopError> {
        let repository = self.repository()?;
        let keys = self.keys()?;
        let entry = document.path().to_string();
        let mut committer =
            AutomaticEntryCommitter::for_entry(&repository, &entry, GitIdentity::ironstorage())
                .map_err(|error| DesktopError::new(DesktopErrorKind::Git, error))?;
        EntryDocumentService::new(&repository, &keys)
            .save_recoverable(document, None, &mut committer)
            .map_err(DesktopError::document)
    }

    pub fn save_active_document(
        &self,
        handle: &NativeAuthenticationHandle,
        document: &EntryDocument,
    ) -> Result<WriteOutcome, DesktopError> {
        handle
            .ensure_active()
            .map_err(|error| DesktopError::new(DesktopErrorKind::Authentication, error))?;
        self.save_document(document)
    }

    fn repository(&self) -> Result<Repository, DesktopError> {
        Repository::open(self.config.vault())
            .map_err(|error| DesktopError::new(DesktopErrorKind::Repository, error))
    }

    fn keys(&self) -> Result<KeyStore, DesktopError> {
        KeyStore::load(self.config.key_material())
            .map_err(|error| DesktopError::new(DesktopErrorKind::KeyMaterial, error))
    }
}

struct ConfigPolicyCommitter<'a> {
    git: AutomaticPolicyCommitter,
    previous: &'a Config,
    replacement: &'a Config,
    persisted: bool,
}

impl PolicyCommitter for ConfigPolicyCommitter<'_> {
    fn commit(&mut self, change: &PolicyCommit) -> Result<(), PolicyCommitError> {
        self.replacement
            .persist()
            .map_err(|error| PolicyCommitError::new(error.to_string()))?;
        match self.git.commit(change) {
            Ok(()) => {
                self.persisted = true;
                Ok(())
            }
            Err(operation) => match self.previous.persist() {
                Ok(()) => Err(operation),
                Err(rollback) => Err(PolicyCommitError::new(format!(
                    "recipient-policy commit failed ({operation}) and configuration rollback failed ({rollback})"
                ))),
            },
        }
    }
}

pub struct DesktopBootstrap {
    storage: DesktopStorage,
    authentication: NativeAuthenticationSession,
    key: KeyInfo,
}

impl DesktopBootstrap {
    pub fn into_parts(self) -> (DesktopStorage, NativeAuthenticationSession, KeyInfo) {
        (self.storage, self.authentication, self.key)
    }
}