//! install: resolve the agent, check dependencies, confirm, run the right
//! installer, and record the installation in the state database.

use super::*;
use crate::events::{Event, EventKind};
use crate::installers;
use crate::runner::SystemRunner;
use anyhow::{anyhow, bail, Result};
use std::collections::BTreeMap;

pub fn run(
    app: &App,
    agent_name: &str,
    method_sel: Option<&str>,
    force: bool,
    provider: Option<&str>,
    model: Option<&str>,
    no_config: bool,
) -> Result<i32> {
    let agent = require_agent(app, agent_name)?;
    let runner = SystemRunner::new(app.dry_run(), app.cli.verbose, &app.log);

    if !agent.supports_current_platform() {
        bail!(
            "agent '{}' is not available on {} (supported: {})",
            agent.name,
            crate::config::current_platform(),
            agent.platforms.join(", ")
        );
    }
    if !agent.installable {
        bail!(
            "agent '{}' is not installable locally{}",
            agent.name,
            agent
                .note
                .as_deref()
                .map(|n| format!(": {n}"))
                .unwrap_or_default()
        );
    }
    let spec = agent
        .install
        .as_ref()
        .ok_or_else(|| anyhow!("agent '{}' has no install definition", agent.name))?;
    let methods = spec.all_methods();
    let method = select_method(&methods, method_sel)?;

    // Provider/model resolution (issue #90): flag > agent.provider >
    // settings.default_provider ; flag --model > agent.model >
    // provider.default_model. Displayed in the summary (and by --dry-run).
    let resolved = resolve_provider_config(app, agent, provider, model)?;
    if no_config {
        app.log
            .info(crate::i18n::tr("--no-config : aucune configuration post-install"));
    } else if !spec.configurable {
        app.log.info(&crate::tr_fmt!(
            "{} ne prend aucune configuration (install.configurable: false)",
            agent.name
        ));
    }

    // Already installed?
    let existing = app.state.get(&agent.name).ok().flatten();
    if existing.is_some() && !force && !app.dry_run() {
        let version = existing
            .as_ref()
            .and_then(|e| e.version.clone())
            .unwrap_or_else(|| "version unknown".to_string());
        bail!(
            "agent '{}' is already installed ({version}); use --force to reinstall, or 'am update {}'",
            agent.name,
            agent.name
        );
    }
    if let Some(e) = &existing {
        if let Some(pid) = e.pid {
            if crate::process::is_running(pid) {
                bail!(
                    "agent '{}' is currently running (pid {pid}); stop it first with 'am stop {}'",
                    agent.name,
                    agent.name
                );
            }
        }
    }

    // Dependencies (checked against real tools unless dry-run).
    crate::deps::ensure_deps(app, agent, &runner)?;

    // Confirmation summary for scripts and destructive actions.
    if !app.dry_run()
        && !app.yes()
        && app.config.settings.confirm_before_run()
        && method.kind == crate::config::InstallType::Curl
    {
        app.log.info(&format!(
            "About to download and run the install script for {}",
            agent.title()
        ));
        app.log
            .info(&format!("  script: {}", method.script.as_deref().unwrap_or("?")));
        if !app.confirm("Run this install script?")? {
            app.log.info("aborted");
            return Ok(0);
        }
    } else if !app.dry_run() && !app.yes() && existing.is_some() {
        app.log.info(&format!(
            "Reinstalling {} via {}",
            agent.title(),
            describe_method(method)
        ));
        if !app.confirm("Proceed with reinstall?")? {
            app.log.info("aborted");
            return Ok(0);
        }
    }

    app.log.info(&format!(
        "installing {} ({})…",
        agent.title(),
        describe_method(method)
    ));
    let mut outcome = installers::run_install(app, agent, method, &runner)?;
    if app.dry_run() {
        app.log.info("dry run complete — nothing was changed");
        return Ok(0);
    }

    // Post-install commands (bin dir first on PATH).
    if !spec.post_install.is_empty() {
        let bin_str = app.paths.bin_dir.display().to_string();
        let mut env = BTreeMap::new();
        if let Ok(path) = std::env::var("PATH") {
            env.insert(
                "PATH".to_string(),
                format!("{bin_str}{}{path}", std::path::MAIN_SEPARATOR),
            );
        }
        for cmd in &spec.post_install {
            let tokens = shell_words::split(cmd)
                .map_err(|e| anyhow!("cannot parse post-install command '{cmd}': {e}"))?;
            if tokens.is_empty() {
                continue;
            }
            let prog = tokens[0].clone();
            let args: Vec<String> = tokens[1..].to_vec();
            app.log.info(&format!("post-install: {cmd}"));
            installers::sh(&runner, &prog, &args, &env, None)?;
        }
    }

    // Fallback version detection.
    if outcome.version.is_none() {
        if let Some(bin) = outcome.bins.first() {
            outcome.version = installers::detect_version(&runner, bin);
        }
    }

    // Post-install provider configuration (issue #91): write the agent
    // config files with the resolved provider/model. Skipped on --no-config
    // and on agents declaring install.configurable: false; never reached in
    // dry-run (returns earlier).
    if !no_config && spec.configurable {
        crate::agent_config::apply_post_install(app, agent, &resolved)?;
    }

    let entry = installers::make_entry(agent, method, &outcome, app);
    let version = entry.version.clone().unwrap_or_else(|| "unknown".to_string());
    app.state.set(&entry)?;
    let mut args = vec![format!("method={}", method.kind)];
    if let Some((p, m)) = &resolved {
        args.push(format!("provider={p}"));
        if let Some(m) = m {
            args.push(format!("model={m}"));
        }
    }
    app.emit(
        &Event::now(EventKind::Install)
            .with_agent(agent.name.clone())
            .with_args(args),
    );
    crate::hooks::run_hooks(
        app,
        "on_install",
        &std::env::current_dir().unwrap_or_default(),
    );
    app.log.success(&format!(
        "installed {} (v{version}) in {}",
        agent.title(),
        entry.install_dir
    ));
    if existing.is_none() {
        app.log.info(&format!(
            "start it with:  am start {}",
            agent.name
        ));
    }
    Ok(0)
}

/// Resolve the provider + model of this install (issue #90) and print what
/// will be configured. Returns (provider, model) when resolved.
///
/// Validation rules:
/// - an explicit `--provider` that is not registered → error listing the
///   registry (the user asked for it by name);
/// - an agent-declared provider that is not registered → warning only
///   (catalog metadata may reference a provider the user has not added yet);
/// - a model absent from the provider's model list → warning, not blocking.
fn resolve_provider_config(
    app: &App,
    agent: &AgentDef,
    flag_provider: Option<&str>,
    flag_model: Option<&str>,
) -> Result<Option<(String, Option<String>)>> {
    let flag_p = flag_provider.filter(|p| !p.is_empty());
    let agent_p = crate::agent_config::provider_pref(agent).filter(|p| !p.is_empty());

    // Explicit provider requested but not registered: hard error.
    if let Some(p) = flag_p {
        if crate::providers::get(&app.config, p).is_none() {
            let known = crate::providers::names(&app.config);
            let hint = if known.is_empty() {
                "am providers add <nom> --base-url <url>".to_string()
            } else {
                known.join(", ")
            };
            bail!(crate::tr_fmt!(
                "provider '{}' inconnu — providers enregistrés: {}",
                p,
                hint
            ));
        }
    }
    // Agent-declared provider not registered: warn (unless the user already
    // overrode it with --provider, which was validated above).
    if let Some(p) = agent_p {
        if flag_p.is_none() && crate::providers::get(&app.config, p).is_none() {
            app.log.warn(&crate::tr_fmt!(
                "provider '{}' (déclaré par {}) non enregistré — voir: am providers add {} --base-url <url>",
                p,
                agent.name,
                p
            ));
            return Ok(None);
        }
    }

    let Some((pname, def, model)) = crate::providers::resolve_for(
        &app.config,
        crate::agent_config::provider_pref(agent),
        agent.model.as_deref(),
        flag_provider,
        flag_model,
    ) else {
        app.log.info(crate::i18n::tr(
            "aucun provider configuré — voir: am providers add <nom> --base-url <url>",
        ));
        return Ok(None);
    };

    // Model not in the provider's list: warn, keep going.
    if let Some(m) = model {
        if !def.models.is_empty() && !def.models.iter().any(|x| x == m) {
            app.log.warn(&crate::tr_fmt!(
                "modèle '{}' absent de la liste du provider '{}' — modèles: {}",
                m,
                pname,
                def.models.join(", ")
            ));
        }
    }
    let model_label = model.unwrap_or("-");
    app.log.info(&crate::tr_fmt!(
        "configuré avec le provider {} (modèle {})",
        pname,
        model_label
    ));
    Ok(Some((pname.to_string(), model.map(String::from))))
}