//! Backup targets (where), sources (what), strategies (when/how) and records (what was produced).
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::DomainError;

#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "lowercase")]
pub enum StorageKind {
    Smb,
    Ftp,
}

impl StorageKind {
    pub fn as_str(self) -> &'static str {
        match self {
            StorageKind::Smb => "smb",
            StorageKind::Ftp => "ftp",
        }
    }
    pub fn parse(s: &str) -> Option<Self> {
        match s {
            "smb" => Some(StorageKind::Smb),
            "ftp" => Some(StorageKind::Ftp),
            _ => None,
        }
    }
}

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct BackupTarget {
    pub id: Uuid,
    pub name: String,
    pub kind: StorageKind,
    pub host: String,
    pub port: Option<u16>,
    /// SMB share name; unused for FTP.
    #[serde(default)]
    pub share: String,
    /// Directory on the share / server.
    #[serde(default)]
    pub path: String,
    #[serde(default)]
    pub username: String,
    /// Plain text in memory, encrypted at rest.
    #[serde(default)]
    pub password: String,
    /// FTPS (explicit TLS) for FTP targets.
    #[serde(default)]
    pub tls: bool,
}

impl BackupTarget {
    pub fn validate(&self) -> Result<(), DomainError> {
        let err = |m: &str| Err(DomainError::Validation(m.into()));
        if self.name.trim().is_empty() {
            return err("target name is required");
        }
        if self.host.trim().is_empty() || self.host.contains(char::is_whitespace) {
            return err("host is invalid");
        }
        if self.kind == StorageKind::Smb && self.share.trim().is_empty() {
            return err("smb share is required");
        }
        if self.path.contains("..") {
            return err("path must not contain '..'");
        }
        Ok(())
    }
}

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum BackupSource {
    /// Content of a persistent volume claim (e.g. Gitea repositories, LFS, attachments).
    VolumeClaim { namespace: String, pvc: String },
    /// `pg_dumpall` executed inside the database pod.
    PostgresDump { namespace: String, pod: String },
    /// All resources of a namespace as YAML.
    KubernetesManifests { namespace: String },
    /// A directory on the host.
    HostPath { path: String },
}

impl BackupSource {
    pub fn validate(&self) -> Result<(), DomainError> {
        let name = |s: &str, what: &str| {
            crate::cluster::validate_k8s_name(s)
                .map_err(|_| DomainError::Validation(format!("invalid {what}")))
        };
        match self {
            BackupSource::VolumeClaim { namespace, pvc } => {
                name(namespace, "namespace").and(name(pvc, "pvc"))
            }
            BackupSource::PostgresDump { namespace, pod } => {
                name(namespace, "namespace").and(name(pod, "pod"))
            }
            BackupSource::KubernetesManifests { namespace } => name(namespace, "namespace"),
            BackupSource::HostPath { path } => (path.starts_with('/') && !path.contains(".."))
                .then_some(())
                .ok_or_else(|| DomainError::Validation("host path must be absolute".into())),
        }
    }

    /// File extension of the produced archive (before optional `.enc`).
    pub fn extension(&self) -> &'static str {
        match self {
            BackupSource::VolumeClaim { .. } | BackupSource::HostPath { .. } => "tar.gz",
            BackupSource::PostgresDump { .. } => "sql.gz",
            BackupSource::KubernetesManifests { .. } => "yaml.gz",
        }
    }
}

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct BackupStrategy {
    pub id: Uuid,
    pub name: String,
    pub source: BackupSource,
    /// 6-field cron expression.
    pub schedule: String,
    pub target_id: Uuid,
    /// Keep the newest N backups on the target.
    pub retention: u32,
    /// Encrypt archives with this passphrase (AES-256, openssl compatible). Encrypted at rest.
    pub passphrase: Option<String>,
    pub enabled: bool,
}

impl BackupStrategy {
    pub fn validate(&self) -> Result<(), DomainError> {
        if self.name.trim().is_empty() {
            return Err(DomainError::Validation("strategy name is required".into()));
        }
        if !(1..=365).contains(&self.retention) {
            return Err(DomainError::Validation(
                "retention must be between 1 and 365".into(),
            ));
        }
        if self
            .passphrase
            .as_ref()
            .is_some_and(|p| p.chars().count() < 12)
        {
            return Err(DomainError::Validation(
                "passphrase must have at least 12 characters".into(),
            ));
        }
        self.source.validate()
    }

    /// Filename prefix on the target: lowercase name with non-alphanumerics replaced by '-'.
    pub fn slug(&self) -> String {
        let mut s: String = self
            .name
            .to_lowercase()
            .chars()
            .map(|c| if c.is_ascii_alphanumeric() { c } else { '-' })
            .collect();
        while s.contains("--") {
            s = s.replace("--", "-");
        }
        s.trim_matches('-').to_string()
    }

    pub fn filename(&self, at: DateTime<Utc>) -> String {
        let enc = if self.passphrase.is_some() {
            ".enc"
        } else {
            ""
        };
        format!(
            "{}_{}.{}{enc}",
            self.slug(),
            at.format("%Y%m%d-%H%M%S"),
            self.source.extension()
        )
    }
}

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct BackupRecord {
    pub id: Uuid,
    pub strategy_id: Uuid,
    pub filename: String,
    pub size_bytes: u64,
    pub sha256: String,
    pub created_at: DateTime<Utc>,
}

#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
pub struct RemoteFile {
    pub name: String,
    pub size_bytes: u64,
}