//! Application context: configuration, catalog, state, paths, logger and
//! shared flags.

use crate::catalog::Catalog;
use crate::cli::Cli;
use crate::config::{self, Config, Settings};
use crate::output::Logger;
use crate::state::StateStore;
use crate::theme::{self, Theme};
use anyhow::{anyhow, Context, Result};
use std::cell::Cell;
use std::io::{IsTerminal, Write};
use std::path::PathBuf;

#[derive(Debug)]
pub struct App {
    pub cli: Cli,
    pub config: Config,
    pub config_origin: Option<PathBuf>,
    pub paths: Paths,
    pub catalog: Catalog,
    pub state: StateStore,
    pub log: Logger,
    /// Active output color theme (switchable at runtime with the REPL
    /// 'theme <name>' command).
    theme: Cell<&'static Theme>,
}

#[derive(Debug, Clone)]
pub struct Paths {
    pub install_dir: PathBuf,
    pub bin_dir: PathBuf,
    pub log_dir: PathBuf,
    pub state_file: PathBuf,
    pub probe_cache_file: PathBuf,
    pub config_dir: Option<PathBuf>,
}

impl Paths {
    pub fn from_settings(settings: &Settings) -> Self {
        let install_dir = settings
            .install_dir
            .as_deref()
            .map(config::expand_path)
            .unwrap_or_else(|| data_dir().join("agents"));
        let log_dir = settings
            .log_dir
            .as_deref()
            .map(config::expand_path)
            .unwrap_or_else(|| state_dir().join("logs"));
        let bin_dir = install_dir.join("bin");
        let state_file = state_dir().join("state.json");
        let probe_cache_file = state_dir().join("probe-cache.json");
        let config_dir = config::user_config_dir();
        Self {
            install_dir,
            bin_dir,
            log_dir,
            state_file,
            probe_cache_file,
            config_dir,
        }
    }

    /// Create every directory the manager needs.
    pub fn ensure(&self) -> Result<()> {
        std::fs::create_dir_all(&self.install_dir)
            .with_context(|| format!("cannot create {}", self.install_dir.display()))?;
        std::fs::create_dir_all(&self.bin_dir)?;
        std::fs::create_dir_all(&self.log_dir)?;
        Ok(())
    }
}

impl App {
    pub fn from_cli(cli: Cli) -> Result<Self> {
        let loaded = config::load(&cli)?;
        let paths = Paths::from_settings(&loaded.config.settings);
        let log = Logger::new(paths.log_dir.clone(), cli.verbose, cli.quiet, cli.no_color);
        let state = StateStore::new(paths.state_file.clone());
        let catalog = Catalog::new(
            loaded.config.agents.clone(),
            loaded.config.aliases.clone(),
            loaded.config.groups.clone(),
        );
        let theme = resolve_theme(cli.theme.as_deref(), loaded.config.settings.theme.as_deref())?;
        Ok(Self {
            cli,
            config: loaded.config,
            config_origin: loaded.origin,
            paths,
            catalog,
            state,
            log,
            theme: Cell::new(theme),
        })
    }

    pub fn dry_run(&self) -> bool {
        self.cli.dry_run
    }

    pub fn json(&self) -> bool {
        self.cli.json
    }

    pub fn yes(&self) -> bool {
        self.cli.yes
    }

    pub fn color(&self) -> bool {
        !self.cli.no_color && std::io::stdout().is_terminal()
    }

    pub fn theme(&self) -> &'static Theme {
        self.theme.get()
    }

    /// Switch the active theme (used by the REPL 'theme <name>' command).
    pub fn set_theme(&self, theme: &'static Theme) {
        self.theme.set(theme);
    }

    /// Ask the user for confirmation on stderr. Accepts y/yes/o/oui.
    pub fn confirm(&self, question: &str) -> Result<bool> {
        if self.cli.yes {
            return Ok(true);
        }
        eprint!("{question} [y/N] ");
        std::io::stderr().flush().ok();
        let mut line = String::new();
        std::io::stdin().read_line(&mut line).ok();
        let answer = line.trim().to_lowercase();
        Ok(matches!(answer.as_str(), "y" | "yes" | "o" | "oui" | "true"))
    }
}

/// Resolve the output color theme: the --theme flag wins, then the
/// configuration entry, then the default theme. An unknown --theme value is
/// an error; an unknown configured value silently falls back to the default.
fn resolve_theme(flag: Option<&str>, configured: Option<&str>) -> Result<&'static Theme> {
    if let Some(name) = flag {
        return theme::find(name).ok_or_else(|| {
            anyhow!(
                "unknown theme '{name}' — available: {}",
                theme::names().join(", ")
            )
        });
    }
    Ok(configured
        .and_then(theme::find)
        .unwrap_or_else(theme::default_theme))
}

/// Root directory for agent data (overridable with AGENT_MANAGER_DATA,
/// mostly used by tests).
pub fn data_dir() -> PathBuf {
    if let Some(d) = std::env::var_os("AGENT_MANAGER_DATA") {
        return PathBuf::from(d);
    }
    if cfg!(windows) {
        let base = std::env::var_os("LOCALAPPDATA")
            .map(PathBuf::from)
            .or_else(|| config::home_dir().map(|h| h.join(".local").join("share")));
        return base
            .map(|b| b.join("agent-manager"))
            .unwrap_or_else(|| PathBuf::from(".agent-manager"));
    }
    if cfg!(target_os = "macos") {
        return config::home_dir()
            .map(|h| h.join("Library").join("Application Support").join("agent-manager"))
            .unwrap_or_else(|| PathBuf::from(".agent-manager"));
    }
    let base = std::env::var_os("XDG_DATA_HOME")
        .map(PathBuf::from)
        .or_else(|| config::home_dir().map(|h| h.join(".local").join("share")));
    base.map(|b| b.join("agent-manager"))
        .unwrap_or_else(|| PathBuf::from(".agent-manager"))
}

/// Root directory for runtime state (logs, state file).
pub fn state_dir() -> PathBuf {
    if let Some(d) = std::env::var_os("AGENT_MANAGER_STATE") {
        return PathBuf::from(d);
    }
    if cfg!(target_os = "linux") {
        let base = std::env::var_os("XDG_STATE_HOME")
            .map(PathBuf::from)
            .or_else(|| config::home_dir().map(|h| h.join(".local").join("state")));
        if let Some(b) = base {
            return b.join("agent-manager");
        }
    }
    data_dir()
}