//! relicario CLI -- the platform layer for the relicario password manager.
//!
//! This binary provides the filesystem, git, and terminal I/O that
//! [`relicario_core`] intentionally excludes. It is the "glue" between the
//! platform-agnostic core library and the user's local environment.
//!
//! ## Vault layout on disk
//!
//! ```text
//! <vault_dir>/
//!   .relicario/
//!     salt            # 32-byte random salt for Argon2id KDF
//!     params.json     # KDF tuning parameters (m, t, p)
//!     devices.json    # registered device public keys
//!   entries/
//!     <id>.enc        # individual encrypted entries
//!   manifest.enc      # encrypted entry index (name, url, username per entry)
//!   .gitignore        # excludes reference.jpg from version control
//!   reference.jpg     # the reference image with embedded secret (gitignored)
//! ```
//!
//! ## Unlock flow
//!
//! Every command that accesses vault data follows this sequence:
//!
//! 1. Locate the reference image (via `RELICARIO_IMAGE` env var or interactive prompt).
//! 2. Prompt for the passphrase (read from stderr, not echoed).
//! 3. Extract the 32-byte image secret from the reference JPEG via DCT steganography.
//! 4. Read the vault salt and KDF params from `.relicario/`.
//! 5. Derive the master key: `Argon2id(passphrase || image_secret, salt, params)`.
//! 6. Use the master key to decrypt the manifest and/or individual entries.
//!
//! ## Git integration
//!
//! The CLI shells out to the `git` binary for all version control operations.
//! This avoids pulling in libgit2 or gitoxide as dependencies, keeping the
//! binary small and the build simple. Every mutation (add, edit, rm, device add/revoke)
//! creates a git commit, preserving an audit log of all vault changes.

use anyhow::{bail, Context, Result};
use clap::{Parser, Subcommand};
use relicario_core::{
    decrypt_entry, decrypt_manifest, encrypt_entry, encrypt_manifest, generate_entry_id,
    Entry, KdfParams, Manifest, ManifestEntry,
};
use zeroize::Zeroizing;
use rand::rngs::OsRng;
use rand::RngCore;
use serde::{Deserialize, Serialize};
use std::fs;
use std::io::{self, BufRead, Write};
use std::path::PathBuf;
use std::process::Command;

// ─── CLI structure ──────────────────────────────────────────────────────────

/// Top-level CLI argument parser.
#[derive(Parser)]
#[command(
    name = "relicario",
    version,
    about = "Git-backed password manager with reference image authentication"
)]
struct Cli {
    #[command(subcommand)]
    command: Commands,
}

/// All available CLI subcommands.
#[derive(Subcommand)]
enum Commands {
    /// Initialize a new relicario vault in the current directory.
    /// Creates the directory structure, generates a random image secret,
    /// embeds it in the carrier image, and sets up git.
    Init {
        /// Path to the carrier JPEG image to embed the secret into.
        #[arg(long)]
        image: PathBuf,
        /// Output path for the reference image (with embedded secret).
        #[arg(long, default_value = "reference.jpg")]
        output: PathBuf,
    },
    /// Add a new password entry to the vault.
    /// Prompts interactively for name, URL, username, password, notes, and TOTP.
    Add,
    /// Get a password entry by name (fuzzy search).
    /// Decrypts and displays the full entry, and copies the password to clipboard
    /// with a 30-second auto-clear.
    Get { name: String },
    /// List all entries in the vault (names, URLs, usernames only -- no passwords).
    List,
    /// Edit an existing entry by name (fuzzy search).
    /// Shows current values and lets you selectively update fields.
    Edit { name: String },
    /// Remove an entry from the vault by name (fuzzy search).
    /// Prompts for confirmation before deleting.
    Rm { name: String },
    /// Sync the vault with the git remote (pull --rebase, then push).
    Sync,
    /// Generate a random password and print it to stdout.
    Generate {
        /// Length of the generated password in characters.
        #[arg(short, long, default_value = "20")]
        length: usize,
    },
    /// Manage device keys (add, list, revoke).
    /// Device ed25519 keys are independent of the vault KDF -- revoking a device
    /// does not require changing the passphrase or reference image.
    Device {
        #[command(subcommand)]
        action: DeviceCommands,
    },
}

/// Subcommands for device key management.
#[derive(Subcommand)]
enum DeviceCommands {
    /// Register a new device by generating an ed25519 keypair.
    /// The private key is saved to the user's config directory;
    /// the public key is added to the vault's devices.json.
    Add {
        /// Human-readable name for this device (e.g., "macbook", "phone").
        #[arg(long)]
        name: String,
    },
    /// List all registered devices and their public keys.
    List,
    /// Revoke a device by removing its public key from devices.json.
    /// This does NOT rotate the vault key -- the device can no longer
    /// authenticate, but the vault encryption is unchanged.
    Revoke { name: String },
}

// ─── Device entry ───────────────────────────────────────────────────────────

/// A registered device, stored in `.relicario/devices.json`.
///
/// Each device has an ed25519 keypair. The private key lives on the device
/// itself (in the user's config directory); only the public key is stored
/// in the vault. This separation means revoking a device is a metadata-only
/// operation that does not affect the vault's encryption key.
#[derive(Debug, Clone, Serialize, Deserialize)]
struct DeviceEntry {
    /// Human-readable device name (e.g., "macbook-pro", "pixel-7").
    name: String,
    /// Hex-encoded ed25519 public key (64 hex chars = 32 bytes).
    public_key: String, // hex-encoded
}

// ─── Helper functions ───────────────────────────────────────────────────────

/// Returns the vault root directory (the current working directory).
/// The vault is always rooted at the directory where `relicario` is invoked.
fn vault_dir() -> PathBuf {
    std::env::current_dir().expect("failed to get current directory")
}

/// Returns the path to the `.relicario/` configuration directory within the vault.
fn relicario_dir() -> PathBuf {
    vault_dir().join(".relicario")
}

/// Read the 32-byte vault salt from `.relicario/salt`.
///
/// The salt is generated once during `init` and is unique per vault. It is
/// not secret (stored in plaintext) -- its purpose is to prevent precomputed
/// rainbow table attacks against the Argon2id KDF.
fn read_salt() -> Result<[u8; 32]> {
    let data = fs::read(relicario_dir().join("salt")).context("failed to read salt")?;
    let mut salt = [0u8; 32];
    if data.len() != 32 {
        bail!("invalid salt file: expected 32 bytes, got {}", data.len());
    }
    salt.copy_from_slice(&data);
    Ok(salt)
}

/// Read the KDF parameters from `.relicario/params.json`.
fn read_params() -> Result<KdfParams> {
    let data = fs::read_to_string(relicario_dir().join("params.json"))
        .context("failed to read params.json")?;
    let params: KdfParams = serde_json::from_str(&data).context("failed to parse params.json")?;
    Ok(params)
}

/// Locate the reference image path.
///
/// First checks the `RELICARIO_IMAGE` environment variable (useful for scripting
/// and testing). If not set, prompts the user interactively.
fn get_image_path() -> Result<PathBuf> {
    if let Ok(path) = std::env::var("RELICARIO_IMAGE") {
        return Ok(PathBuf::from(path));
    }
    let path = prompt("Reference image path")?;
    Ok(PathBuf::from(path))
}

/// Perform the two-factor unlock sequence and return the derived master key.
///
/// This is the core authentication flow used by every vault-access command:
/// 1. Prompt for the passphrase (via rpassword, not echoed to terminal).
/// 2. Read and decode the reference JPEG, extracting the steganographic secret.
/// 3. Load the vault salt and KDF params.
/// 4. Derive the master key via Argon2id(passphrase || image_secret, salt).
fn unlock(image_path: &PathBuf) -> Result<Zeroizing<[u8; 32]>> {
    let passphrase = rpassword::prompt_password_stderr("Passphrase: ").context("failed to read passphrase")?;

    let jpeg_data = fs::read(image_path).context("failed to read reference image")?;
    let image_secret =
        relicario_core::imgsecret::extract(&jpeg_data).context("failed to extract image secret")?;

    let salt = read_salt()?;
    let params = read_params()?;

    let master_key = relicario_core::derive_master_key(passphrase.as_bytes(), &image_secret, &salt, &params)
        .context("failed to derive master key")?;

    Ok(master_key)
}

/// Decrypt and return the vault manifest.
fn read_manifest(key: &[u8; 32]) -> Result<Manifest> {
    let data = fs::read(vault_dir().join("manifest.enc")).context("failed to read manifest.enc")?;
    let manifest = decrypt_manifest(key, &data).context("failed to decrypt manifest")?;
    Ok(manifest)
}

/// Encrypt and write the vault manifest to disk.
fn write_manifest(key: &[u8; 32], manifest: &Manifest) -> Result<()> {
    let data = encrypt_manifest(key, manifest).context("failed to encrypt manifest")?;
    fs::write(vault_dir().join("manifest.enc"), data).context("failed to write manifest.enc")?;
    Ok(())
}

/// Stage all changes and create a git commit with the given message.
///
/// Every vault mutation is committed to preserve a full audit log in git history.
/// The CLI shells out to the `git` binary rather than using a Rust git library
/// to keep dependencies minimal.
fn git_commit(message: &str) -> Result<()> {
    let status = Command::new("git")
        .args(["add", "-A"])
        .status()
        .context("failed to run git add")?;
    if !status.success() {
        bail!("git add failed");
    }

    let status = Command::new("git")
        .args(["commit", "-m", message])
        .status()
        .context("failed to run git commit")?;
    if !status.success() {
        bail!("git commit failed");
    }

    Ok(())
}

/// Return the current time as a Unix timestamp string.
///
/// Uses seconds since epoch rather than a formatted ISO 8601 string to avoid
/// pulling in chrono or time crate dependencies.
fn now_iso8601() -> String {
    let duration = std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .unwrap_or_default();
    format!("{}", duration.as_secs())
}

/// Prompt the user for input via stderr (so stdout remains clean for piping).
fn prompt(message: &str) -> Result<String> {
    eprint!("{}: ", message);
    io::stderr().flush()?;
    let mut line = String::new();
    io::stdin().lock().read_line(&mut line)?;
    Ok(line.trim().to_string())
}

/// Prompt for an optional field. Returns `None` if the user enters an empty string.
fn prompt_optional(message: &str) -> Result<Option<String>> {
    let value = prompt(message)?;
    if value.is_empty() {
        Ok(None)
    } else {
        Ok(Some(value))
    }
}

/// Prompt for a field with a default value shown in brackets.
/// If the user presses Enter without typing, the current value is kept.
fn prompt_with_default(field: &str, current: &str) -> Result<String> {
    eprint!("{} [{}]: ", field, current);
    io::stderr().flush()?;
    let mut line = String::new();
    io::stdin().lock().read_line(&mut line)?;
    let trimmed = line.trim();
    if trimmed.is_empty() {
        Ok(current.to_string())
    } else {
        Ok(trimmed.to_string())
    }
}

/// Generate a random password of the given length using a mixed character set.
///
/// The charset includes lowercase, uppercase, digits, and common symbols.
/// Each character is selected uniformly at random via the OS CSPRNG.
fn generate_password(length: usize) -> String {
    const CHARSET: &[u8] = b"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_=+";
    let mut rng = OsRng;
    (0..length)
        .map(|_| {
            let idx = (rng.next_u32() as usize) % CHARSET.len();
            CHARSET[idx] as char
        })
        .collect()
}

// ─── Command implementations ────────────────────────────────────────────────

/// Initialize a new relicario vault in the current directory.
///
/// Full sequence:
/// 1. Read the carrier JPEG provided by the user.
/// 2. Generate a random 32-byte image secret.
/// 3. Embed the secret into the carrier via DCT steganography.
/// 4. Save the resulting reference JPEG (this is the user's second factor).
/// 5. Prompt for a passphrase (minimum 8 characters, with confirmation).
/// 6. Generate a random 32-byte salt.
/// 7. Derive the master key from passphrase + image_secret + salt.
/// 8. Create the vault directory structure (.relicario/, entries/).
/// 9. Write salt, KDF params, empty devices list, and encrypted empty manifest.
/// 10. Initialize git and create the first commit.
fn cmd_init(image: PathBuf, output: PathBuf) -> Result<()> {
    // 1. Read carrier JPEG
    let carrier = fs::read(&image).context("failed to read carrier image")?;

    // 2. Generate random image_secret
    let mut image_secret = [0u8; 32];
    OsRng.fill_bytes(&mut image_secret);

    // 3. Embed secret into carrier
    let reference_jpeg =
        relicario_core::imgsecret::embed(&carrier, &image_secret).context("failed to embed secret")?;

    // 4. Save reference JPEG
    fs::write(&output, &reference_jpeg).context("failed to write reference image")?;
    eprintln!("Reference image saved to {}", output.display());

    // 5. Prompt for passphrase
    let passphrase = loop {
        let p1 = rpassword::prompt_password_stderr("Passphrase (min 8 chars): ")
            .context("failed to read passphrase")?;
        if p1.len() < 8 {
            eprintln!("Passphrase must be at least 8 characters.");
            continue;
        }
        let p2 = rpassword::prompt_password_stderr("Confirm passphrase: ")
            .context("failed to read passphrase confirmation")?;
        if p1 != p2 {
            eprintln!("Passphrases do not match.");
            continue;
        }
        break p1;
    };

    // 6. Generate random salt
    let mut salt = [0u8; 32];
    OsRng.fill_bytes(&mut salt);

    // 7. Derive master key
    let params = KdfParams::default();
    let master_key = relicario_core::derive_master_key(passphrase.as_bytes(), &image_secret, &salt, &params)
        .context("failed to derive master key")?;

    // 8. Create directory structure
    let relicario = relicario_dir();
    fs::create_dir_all(&relicario).context("failed to create .relicario directory")?;
    fs::create_dir_all(vault_dir().join("entries")).context("failed to create entries directory")?;

    // 9. Write config files
    fs::write(relicario.join("salt"), &salt).context("failed to write salt")?;
    fs::write(
        relicario.join("params.json"),
        serde_json::to_string_pretty(&params)?,
    )
    .context("failed to write params.json")?;
    fs::write(relicario.join("devices.json"), "[]").context("failed to write devices.json")?;

    // 10. Encrypt empty manifest
    let manifest = Manifest::new();
    let manifest_enc = encrypt_manifest(&*master_key, &manifest).context("failed to encrypt manifest")?;
    fs::write(vault_dir().join("manifest.enc"), manifest_enc)
        .context("failed to write manifest.enc")?;

    // 11. Create .gitignore (exclude reference image from version control --
    //     it contains the steganographic secret and must be kept offline)
    fs::write(vault_dir().join(".gitignore"), "reference.jpg\n")
        .context("failed to write .gitignore")?;

    // 12. Git init and commit
    let status = Command::new("git").arg("init").status()?;
    if !status.success() {
        bail!("git init failed");
    }
    git_commit("feat: initialize relicario vault")?;

    // 13. Success
    eprintln!("Vault initialized successfully.");
    eprintln!("IMPORTANT: Keep your reference image safe — you need it to unlock the vault.");

    Ok(())
}

/// Generate a random password and print it to stdout.
fn cmd_generate(length: usize) -> Result<()> {
    println!("{}", generate_password(length));
    Ok(())
}

/// Add a new entry to the vault.
///
/// Prompts for all fields, encrypts the entry, writes it to `entries/<id>.enc`,
/// updates the manifest, and commits the change to git.
fn cmd_add() -> Result<()> {
    let image_path = get_image_path()?;
    let master_key = unlock(&image_path)?;

    let name = prompt("Name")?;
    if name.is_empty() {
        bail!("Name cannot be empty");
    }

    let url = prompt_optional("URL (optional)")?;
    let username = prompt_optional("Username (optional)")?;

    let password = {
        let p = prompt_optional("Password (Enter to auto-generate)")?;
        match p {
            Some(pw) if !pw.is_empty() => pw,
            _ => {
                let gen = generate_password(20);
                eprintln!("Generated password: {}", gen);
                gen
            }
        }
    };

    let notes = prompt_optional("Notes (optional)")?;
    let totp_secret = prompt_optional("TOTP secret (optional)")?;

    let now = now_iso8601();
    let entry = Entry {
        name: name.clone(),
        url: url.clone(),
        username: username.clone(),
        password,
        notes,
        totp_secret,
        group: None,
        created_at: now.clone(),
        updated_at: now.clone(),
    };

    let entry_id = generate_entry_id();
    let encrypted = encrypt_entry(&*master_key, &entry).context("failed to encrypt entry")?;
    fs::write(
        vault_dir().join("entries").join(format!("{}.enc", entry_id)),
        encrypted,
    )
    .context("failed to write entry file")?;

    let mut manifest = read_manifest(&*master_key)?;
    manifest.add_entry(
        entry_id.clone(),
        ManifestEntry {
            name: name.clone(),
            url,
            username,
            group: None,
            updated_at: now,
        },
    );
    write_manifest(&*master_key, &manifest)?;

    git_commit(&format!("feat: add entry '{}'", name))?;
    eprintln!("Entry '{}' added (id: {})", name, entry_id);

    Ok(())
}

/// Search the manifest for entries matching a query and let the user select one.
///
/// If exactly one entry matches, it is returned immediately. If multiple match,
/// the user is shown a numbered list and prompted to choose.
fn search_and_select(manifest: &Manifest, query: &str) -> Result<(String, ManifestEntry)> {
    let results = manifest.search(query);
    if results.is_empty() {
        bail!("no entries matching '{}'", query);
    }

    if results.len() == 1 {
        let (id, entry) = results[0];
        return Ok((id.clone(), entry.clone()));
    }

    eprintln!("Multiple matches:");
    for (i, (id, entry)) in results.iter().enumerate() {
        eprintln!(
            "  {}) {} (id: {}, url: {})",
            i + 1,
            entry.name,
            id,
            entry.url.as_deref().unwrap_or("-")
        );
    }

    let choice = prompt("Choose entry number")?;
    let idx: usize = choice.parse::<usize>().context("invalid number")? - 1;
    if idx >= results.len() {
        bail!("invalid selection");
    }

    let (id, entry) = results[idx];
    Ok((id.clone(), entry.clone()))
}

/// Retrieve and display a vault entry, and copy its password to the clipboard.
///
/// The password is auto-cleared from the clipboard after 30 seconds to limit
/// exposure. The clipboard clear is best-effort (a background thread checks
/// whether the clipboard still contains the password before clearing).
fn cmd_get(query: String) -> Result<()> {
    let image_path = get_image_path()?;
    let master_key = unlock(&image_path)?;

    let manifest = read_manifest(&*master_key)?;
    let (entry_id, _) = search_and_select(&manifest, &query)?;

    let data = fs::read(vault_dir().join("entries").join(format!("{}.enc", entry_id)))
        .context("failed to read entry file")?;
    let entry = decrypt_entry(&*master_key, &data).context("failed to decrypt entry")?;

    println!("Name:     {}", entry.name);
    println!(
        "URL:      {}",
        entry.url.as_deref().unwrap_or("-")
    );
    println!(
        "Username: {}",
        entry.username.as_deref().unwrap_or("-")
    );
    println!("Password: {}", entry.password);
    if let Some(notes) = &entry.notes {
        println!("Notes:    {}", notes);
    }
    if let Some(totp) = &entry.totp_secret {
        println!("TOTP:     {}", totp);
    }

    // Copy password to clipboard with 30s TTL.
    // Uses arboard for cross-platform clipboard access.
    // The clear is done in a background thread: after 30 seconds, if the
    // clipboard still contains this password, it is replaced with an empty string.
    match arboard::Clipboard::new() {
        Ok(mut clipboard) => {
            if clipboard.set_text(&entry.password).is_ok() {
                eprintln!("Password copied to clipboard (clearing in 30s)");
                let pw = entry.password.clone();
                std::thread::spawn(move || {
                    std::thread::sleep(std::time::Duration::from_secs(30));
                    if let Ok(mut cb) = arboard::Clipboard::new() {
                        if let Ok(current) = cb.get_text() {
                            if current == pw {
                                let _ = cb.set_text("");
                            }
                        }
                    }
                });
            }
        }
        Err(_) => {
            eprintln!("(clipboard unavailable)");
        }
    }

    Ok(())
}

/// List all vault entries in alphabetical order.
///
/// Only shows non-sensitive metadata (name, URL, username) from the manifest.
/// Individual entry files are not decrypted.
fn cmd_list() -> Result<()> {
    let image_path = get_image_path()?;
    let master_key = unlock(&image_path)?;

    let manifest = read_manifest(&*master_key)?;

    let mut entries: Vec<_> = manifest.entries.iter().collect();
    entries.sort_by(|a, b| a.1.name.to_lowercase().cmp(&b.1.name.to_lowercase()));

    if entries.is_empty() {
        eprintln!("No entries in vault.");
        return Ok(());
    }

    println!("{:<10} {:<30} {:<30} {}", "ID", "Name", "URL", "Username");
    println!("{}", "-".repeat(80));
    for (id, entry) in entries {
        println!(
            "{:<10} {:<30} {:<30} {}",
            id,
            entry.name,
            entry.url.as_deref().unwrap_or("-"),
            entry.username.as_deref().unwrap_or("-")
        );
    }

    Ok(())
}

/// Edit an existing entry by searching for it, showing current values, and
/// prompting for new values. Unchanged fields keep their current value.
fn cmd_edit(query: String) -> Result<()> {
    let image_path = get_image_path()?;
    let master_key = unlock(&image_path)?;

    let manifest = read_manifest(&*master_key)?;
    let (entry_id, _) = search_and_select(&manifest, &query)?;

    let data = fs::read(vault_dir().join("entries").join(format!("{}.enc", entry_id)))
        .context("failed to read entry file")?;
    let entry = decrypt_entry(&*master_key, &data).context("failed to decrypt entry")?;

    eprintln!("Editing '{}' (Enter to keep current value)", entry.name);

    let name = prompt_with_default("Name", &entry.name)?;
    let url = prompt_with_default("URL", entry.url.as_deref().unwrap_or(""))?;
    let url = if url.is_empty() { None } else { Some(url) };
    let username = prompt_with_default("Username", entry.username.as_deref().unwrap_or(""))?;
    let username = if username.is_empty() {
        None
    } else {
        Some(username)
    };
    let password = prompt_with_default("Password", &entry.password)?;
    let notes = prompt_with_default("Notes", entry.notes.as_deref().unwrap_or(""))?;
    let notes = if notes.is_empty() { None } else { Some(notes) };
    let totp_secret = prompt_with_default("TOTP secret", entry.totp_secret.as_deref().unwrap_or(""))?;
    let totp_secret = if totp_secret.is_empty() {
        None
    } else {
        Some(totp_secret)
    };

    let now = now_iso8601();
    let updated_entry = Entry {
        name: name.clone(),
        url: url.clone(),
        username: username.clone(),
        password,
        notes,
        totp_secret,
        group: entry.group,
        created_at: entry.created_at,
        updated_at: now.clone(),
    };

    let encrypted = encrypt_entry(&*master_key, &updated_entry).context("failed to encrypt entry")?;
    fs::write(
        vault_dir().join("entries").join(format!("{}.enc", entry_id)),
        encrypted,
    )
    .context("failed to write entry file")?;

    let mut manifest = read_manifest(&*master_key)?;
    manifest.add_entry(
        entry_id,
        ManifestEntry {
            name: name.clone(),
            url,
            username,
            group: updated_entry.group,
            updated_at: now,
        },
    );
    write_manifest(&*master_key, &manifest)?;

    git_commit(&format!("feat: edit entry '{}'", name))?;
    eprintln!("Entry '{}' updated.", name);

    Ok(())
}

/// Remove an entry from the vault after confirmation.
///
/// Deletes the encrypted entry file, removes the entry from the manifest,
/// and commits the change to git.
fn cmd_rm(query: String) -> Result<()> {
    let image_path = get_image_path()?;
    let master_key = unlock(&image_path)?;

    let manifest = read_manifest(&*master_key)?;
    let (entry_id, entry) = search_and_select(&manifest, &query)?;

    let confirm = prompt(&format!("Delete '{}' (id: {})? [y/N]", entry.name, entry_id))?;
    if confirm.to_lowercase() != "y" {
        eprintln!("Cancelled.");
        return Ok(());
    }

    let entry_path = vault_dir()
        .join("entries")
        .join(format!("{}.enc", entry_id));
    if entry_path.exists() {
        fs::remove_file(&entry_path).context("failed to remove entry file")?;
    }

    let mut manifest = read_manifest(&*master_key)?;
    manifest.remove_entry(&entry_id);
    write_manifest(&*master_key, &manifest)?;

    git_commit(&format!("feat: remove entry '{}'", entry.name))?;
    eprintln!("Entry '{}' removed.", entry.name);

    Ok(())
}

/// Sync the vault with the git remote.
///
/// Performs `git pull --rebase` followed by `git push`. Rebase is used instead
/// of merge to keep the commit history linear, which is important for the
/// audit log use case.
fn cmd_sync() -> Result<()> {
    eprintln!("Pulling...");
    let status = Command::new("git")
        .args(["pull", "--rebase"])
        .status()
        .context("failed to run git pull")?;
    if !status.success() {
        bail!("git pull --rebase failed");
    }

    eprintln!("Pushing...");
    let status = Command::new("git")
        .arg("push")
        .status()
        .context("failed to run git push")?;
    if !status.success() {
        bail!("git push failed");
    }

    eprintln!("Sync complete.");
    Ok(())
}

// ─── Device management ──────────────────────────────────────────────────────

/// Read the device registry from `.relicario/devices.json`.
fn read_devices() -> Result<Vec<DeviceEntry>> {
    let path = relicario_dir().join("devices.json");
    let data = fs::read_to_string(&path).context("failed to read devices.json")?;
    let devices: Vec<DeviceEntry> = serde_json::from_str(&data).context("failed to parse devices.json")?;
    Ok(devices)
}

/// Write the device registry to `.relicario/devices.json`.
fn write_devices(devices: &[DeviceEntry]) -> Result<()> {
    let data = serde_json::to_string_pretty(devices)?;
    fs::write(relicario_dir().join("devices.json"), data).context("failed to write devices.json")?;
    Ok(())
}

/// Register a new device by generating an ed25519 keypair.
///
/// The private key is saved to `~/.config/relicario/<name>.key` with
/// restrictive permissions (0600 on Unix). The public key is added to
/// the vault's devices.json and committed to git.
///
/// Device keys are independent of the vault encryption key -- revoking a
/// device does not require rotating the passphrase or reference image.
fn cmd_device_add(name: String) -> Result<()> {
    use ed25519_dalek::SigningKey;

    let mut devices = read_devices()?;

    // Check for duplicate device names
    if devices.iter().any(|d| d.name == name) {
        bail!("device '{}' already exists", name);
    }

    // Generate ed25519 keypair using the OS CSPRNG
    let signing_key = SigningKey::generate(&mut OsRng);
    let verifying_key = signing_key.verifying_key();

    let private_key_hex = hex::encode(signing_key.to_bytes());
    let public_key_hex = hex::encode(verifying_key.to_bytes());

    // Save private key to the user's config directory (NOT in the vault)
    let config_dir = dirs::config_dir()
        .context("failed to find config directory")?
        .join("relicario");
    fs::create_dir_all(&config_dir).context("failed to create config directory")?;
    let key_path = config_dir.join(format!("{}.key", name));
    fs::write(&key_path, &private_key_hex).context("failed to write private key")?;

    // Set restrictive permissions on the key file (Unix only)
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        fs::set_permissions(&key_path, fs::Permissions::from_mode(0o600))?;
    }

    // Add public key to the vault's device registry
    devices.push(DeviceEntry {
        name: name.clone(),
        public_key: public_key_hex,
    });
    write_devices(&devices)?;

    git_commit(&format!("feat: add device '{}'", name))?;
    eprintln!("Device '{}' added.", name);
    eprintln!("Private key saved to {}", key_path.display());

    Ok(())
}

/// List all registered devices with their public keys.
fn cmd_device_list() -> Result<()> {
    let devices = read_devices()?;

    if devices.is_empty() {
        eprintln!("No devices registered.");
        return Ok(());
    }

    println!("{:<20} {}", "Name", "Public Key");
    println!("{}", "-".repeat(60));
    for device in &devices {
        println!("{:<20} {}", device.name, device.public_key);
    }

    Ok(())
}

/// Revoke a device by removing it from the device registry.
///
/// This is a metadata-only operation: the device's public key is removed from
/// devices.json, but the vault encryption key is NOT rotated. The revoked
/// device can no longer authenticate via its ed25519 key, but if it had
/// previously derived the master key (via passphrase + image), that key
/// remains valid until the user changes their passphrase or reference image.
fn cmd_device_revoke(name: String) -> Result<()> {
    let mut devices = read_devices()?;
    let initial_len = devices.len();
    devices.retain(|d| d.name != name);

    if devices.len() == initial_len {
        bail!("device '{}' not found", name);
    }

    write_devices(&devices)?;
    git_commit(&format!("feat: revoke device '{}'", name))?;
    eprintln!("Device '{}' revoked.", name);

    Ok(())
}

// ─── Main ───────────────────────────────────────────────────────────────────

/// Entry point: parse CLI arguments and dispatch to the appropriate command handler.
fn main() -> Result<()> {
    let cli = Cli::parse();

    match cli.command {
        Commands::Init { image, output } => cmd_init(image, output),
        Commands::Add => cmd_add(),
        Commands::Get { name } => cmd_get(name),
        Commands::List => cmd_list(),
        Commands::Edit { name } => cmd_edit(name),
        Commands::Rm { name } => cmd_rm(name),
        Commands::Sync => cmd_sync(),
        Commands::Generate { length } => cmd_generate(length),
        Commands::Device { action } => match action {
            DeviceCommands::Add { name } => cmd_device_add(name),
            DeviceCommands::List => cmd_device_list(),
            DeviceCommands::Revoke { name } => cmd_device_revoke(name),
        },
    }
}