use anyhow::Context;
use codex_config::config_toml::ConfigLockfileToml;
use codex_config::config_toml::ConfigToml;
use codex_config::types::MemoriesToml;
use codex_features::AppsMcpPathOverrideConfigToml;
use codex_features::Feature;
use codex_features::FeatureToml;
use codex_features::FeaturesToml;
use codex_features::MultiAgentV2ConfigToml;
use codex_protocol::ThreadId;

use crate::config::Config;
use crate::config_lock::ConfigLockReplayOptions;
use crate::config_lock::clear_config_lock_debug_controls;
use crate::config_lock::config_lockfile;
use crate::config_lock::toml_round_trip;
use crate::config_lock::validate_config_lock_replay;

use super::SessionConfiguration;

pub(crate) async fn validate_config_lock_if_configured(
    session_configuration: &SessionConfiguration,
) -> anyhow::Result<()> {
    if session_configuration.session_source.is_non_root_agent() {
        return Ok(());
    }
    let Some(expected) = session_configuration
        .original_config_do_not_use
        .config_lock_toml
        .as_ref()
    else {
        return Ok(());
    };
    let actual = session_configuration.to_config_lockfile_toml()?;
    let config = session_configuration.original_config_do_not_use.as_ref();
    let options = ConfigLockReplayOptions {
        allow_codex_version_mismatch: config.config_lock_allow_codex_version_mismatch,
    };
    validate_config_lock_replay(expected, &actual, options)
        .context("config lock replay validation failed")?;
    Ok(())
}

pub(crate) async fn export_config_lock_if_configured(
    session_configuration: &SessionConfiguration,
    conversation_id: ThreadId,
) -> anyhow::Result<()> {
    let config = session_configuration.original_config_do_not_use.as_ref();
    let Some(export_dir) = config.config_lock_export_dir.as_ref() else {
        return Ok(());
    };

    let lock = session_configuration.to_config_lockfile_toml()?;
    let lock = toml::to_string_pretty(&lock).context("failed to serialize config lock")?;
    let path = export_dir.join(format!("{conversation_id}.config.lock.toml"));

    tokio::fs::create_dir_all(export_dir)
        .await
        .with_context(|| {
            format!(
                "failed to create config lock export directory {}",
                export_dir.display()
            )
        })?;
    tokio::fs::write(&path, lock)
        .await
        .with_context(|| format!("failed to write config lock to {}", path.display()))?;

    Ok(())
}

impl SessionConfiguration {
    pub(crate) fn to_config_lockfile_toml(&self) -> anyhow::Result<ConfigLockfileToml> {
        Ok(config_lockfile(session_configuration_to_lock_config_toml(
            self,
        )?))
    }
}

fn session_configuration_to_lock_config_toml(
    sc: &SessionConfiguration,
) -> anyhow::Result<ConfigToml> {
    let config = sc.original_config_do_not_use.as_ref();
    // Start from the resolved layer stack, then patch in values that are only
    // known after session setup. Export and replay validation both use this
    // path, so every field here is part of the lockfile contract.
    let mut lock_config: ConfigToml = config
        .config_layer_stack
        .effective_config()
        .try_into()
        .context("failed to deserialize effective config for config lock")?;

    if config.config_lock_save_fields_resolved_from_model_catalog {
        save_session_resolved_fields(sc, &mut lock_config);
    }

    save_config_resolved_fields(config, &mut lock_config)?;
    drop_lockfile_inputs(&mut lock_config);

    Ok(lock_config)
}

/// Saves values chosen during session construction from the model catalog,
/// collaboration mode, and resolved prompt setup.
///
/// These values are not always present in the raw layer stack, so copy them
/// from the live session when the lockfile should be fully self-contained.
fn save_session_resolved_fields(sc: &SessionConfiguration, lock_config: &mut ConfigToml) {
    lock_config.model = Some(sc.collaboration_mode.model().to_string());
    lock_config.model_reasoning_effort = sc.collaboration_mode.reasoning_effort();
    lock_config.model_reasoning_summary = sc.model_reasoning_summary;
    lock_config.service_tier = sc.service_tier.clone();
    lock_config.instructions = Some(sc.base_instructions.clone());
    lock_config.developer_instructions = sc.developer_instructions.clone();
    lock_config.compact_prompt = sc.compact_prompt.clone();
    lock_config.personality = sc.personality;
    lock_config.approval_policy = Some(sc.approval_policy.value());
    lock_config.approvals_reviewer = Some(sc.approvals_reviewer);
}

/// Saves values stored on `Config` after higher-level resolution,
/// normalization, defaulting, or feature materialization.
///
/// Persist the resolved representation so replay compares against the behavior
/// Codex actually ran with, not only the user-authored TOML inputs.
fn save_config_resolved_fields(
    config: &Config,
    lock_config: &mut ConfigToml,
) -> anyhow::Result<()> {
    lock_config.web_search = Some(config.web_search_mode.value());
    lock_config.model_provider = Some(config.model_provider_id.clone());
    lock_config.plan_mode_reasoning_effort = config.plan_mode_reasoning_effort;
    lock_config.model_verbosity = config.model_verbosity;
    lock_config.include_permissions_instructions = Some(config.include_permissions_instructions);
    lock_config.include_apps_instructions = Some(config.include_apps_instructions);
    lock_config.include_collaboration_mode_instructions =
        Some(config.include_collaboration_mode_instructions);
    lock_config.include_environment_context = Some(config.include_environment_context);
    lock_config.background_terminal_max_timeout = Some(config.background_terminal_max_timeout);

    // Feature aliases and feature configs need to be written in their resolved
    // form; otherwise replay can drift when a legacy key maps to the same
    // runtime feature.
    let features = lock_config
        .features
        .get_or_insert_with(FeaturesToml::default);
    features.materialize_resolved_enabled(config.features.get());
    let mut multi_agent_v2: MultiAgentV2ConfigToml =
        resolved_config_to_toml(&config.multi_agent_v2, "features.multi_agent_v2")?;
    multi_agent_v2.enabled = Some(config.features.enabled(Feature::MultiAgentV2));
    features.multi_agent_v2 = Some(FeatureToml::Config(multi_agent_v2));
    features.apps_mcp_path_override = Some(FeatureToml::Config(AppsMcpPathOverrideConfigToml {
        enabled: Some(config.features.enabled(Feature::AppsMcpPathOverride)),
        path: config.apps_mcp_path_override.clone(),
    }));
    lock_config.memories = Some(resolved_config_to_toml::<MemoriesToml>(
        &config.memories,
        "memories",
    )?);

    let agents = lock_config.agents.get_or_insert_with(Default::default);
    // Multi-agent v2 owns thread fanout through its feature config. Preserve
    // the legacy agents.max_threads setting only when v2 is disabled.
    agents.max_threads = if config.features.enabled(Feature::MultiAgentV2) {
        None
    } else {
        config.agent_max_threads
    };
    agents.max_depth = Some(config.agent_max_depth);
    agents.job_max_runtime_seconds = config.agent_job_max_runtime_seconds;
    agents.interrupt_message = Some(config.agent_interrupt_message_enabled);

    lock_config
        .skills
        .get_or_insert_with(Default::default)
        .include_instructions = Some(config.include_skill_instructions);

    Ok(())
}

fn drop_lockfile_inputs(lock_config: &mut ConfigToml) {
    // The lockfile should contain replayable values, not the profile,
    // debug-control, file-include, and environment-specific inputs that
    // produced those values in the original session.
    lock_config.profile = None;
    lock_config.profiles.clear();
    clear_config_lock_debug_controls(lock_config);
    lock_config.model_instructions_file = None;
    lock_config.experimental_instructions_file = None;
    lock_config.experimental_compact_prompt_file = None;
    lock_config.model_catalog_json = None;
    lock_config.sandbox_mode = None;
    lock_config.sandbox_workspace_write = None;
    lock_config.default_permissions = None;
    lock_config.permissions = None;
    lock_config.experimental_use_unified_exec_tool = None;
}

fn resolved_config_to_toml<Toml>(
    value: &impl serde::Serialize,
    label: &'static str,
) -> anyhow::Result<Toml>
where
    Toml: serde::de::DeserializeOwned + serde::Serialize,
{
    toml_round_trip(value, label).map_err(anyhow::Error::from)
}

#[cfg(test)]
mod tests {
    use super::*;
    use pretty_assertions::assert_eq;
    use std::sync::Arc;

    #[tokio::test]
    async fn lock_contains_prompts_and_materializes_features() {
        let mut sc = crate::session::tests::make_session_configuration_for_tests().await;
        sc.base_instructions = "resolved instructions".to_string();
        sc.developer_instructions = Some("resolved developer instructions".to_string());
        sc.compact_prompt = Some("resolved compact prompt".to_string());

        let lockfile = sc.to_config_lockfile_toml().expect("lock should serialize");
        let lock = &lockfile.config;

        assert_eq!(lock.instructions, Some(sc.base_instructions.clone()));
        assert_eq!(lock.developer_instructions, sc.developer_instructions);
        assert_eq!(lock.compact_prompt, sc.compact_prompt);
        assert_eq!(lock.model, Some(sc.collaboration_mode.model().to_string()));
        assert_eq!(
            lock.model_reasoning_effort,
            sc.collaboration_mode.reasoning_effort()
        );
        assert_eq!(lock.profile, None);
        assert!(lock.profiles.is_empty());
        assert!(
            lock.debug
                .as_ref()
                .is_none_or(|debug| debug.config_lockfile.is_none())
        );
        assert!(lock.memories.is_some());

        let features = lock
            .features
            .as_ref()
            .expect("lock should materialize feature states");
        let feature_entries = features.entries();
        for spec in codex_features::FEATURES {
            assert_eq!(
                feature_entries.get(spec.key),
                Some(&sc.original_config_do_not_use.features.enabled(spec.id)),
                "{}",
                spec.key
            );
        }

        let multi_agent_v2 = features
            .multi_agent_v2
            .as_ref()
            .expect("multi_agent_v2 config should be materialized");
        assert!(matches!(
            multi_agent_v2,
            FeatureToml::Config(MultiAgentV2ConfigToml {
                enabled: Some(false),
                max_concurrent_threads_per_session: Some(_),
                min_wait_timeout_ms: Some(_),
                max_wait_timeout_ms: Some(_),
                default_wait_timeout_ms: Some(_),
                usage_hint_enabled: Some(_),
                hide_spawn_agent_metadata: Some(_),
                ..
            })
        ));

        assert_eq!(lockfile.version, crate::config_lock::CONFIG_LOCK_VERSION);
    }

    #[tokio::test]
    async fn lock_skips_session_values_when_model_catalog_fields_are_not_saved() {
        let mut sc = crate::session::tests::make_session_configuration_for_tests().await;
        let mut config = (*sc.original_config_do_not_use).clone();
        config.config_lock_save_fields_resolved_from_model_catalog = false;
        sc.original_config_do_not_use = Arc::new(config);
        sc.base_instructions = "catalog instructions".to_string();
        sc.developer_instructions = Some("catalog developer instructions".to_string());
        sc.compact_prompt = Some("catalog compact prompt".to_string());
        sc.service_tier = Some("flex".to_string());

        let lockfile = sc.to_config_lockfile_toml().expect("lock should serialize");
        let lock = &lockfile.config;

        assert_eq!(lock.model, None);
        assert_eq!(lock.model_reasoning_effort, None);
        assert_eq!(lock.model_reasoning_summary, None);
        assert_eq!(lock.service_tier, None);
        assert_eq!(lock.instructions, None);
        assert_eq!(lock.developer_instructions, None);
        assert_eq!(lock.compact_prompt, None);
        assert_eq!(lock.personality, None);
        assert_eq!(lock.approval_policy, None);
        assert_eq!(lock.approvals_reviewer, None);
    }

    #[tokio::test]
    async fn lock_validation_reports_config_diff() {
        let sc = crate::session::tests::make_session_configuration_for_tests().await;
        let expected = sc.to_config_lockfile_toml().expect("lock should serialize");
        let mut actual = expected.clone();
        actual.config.model = Some("different-model".to_string());

        let error =
            validate_config_lock_replay(&expected, &actual, ConfigLockReplayOptions::default())
                .expect_err("config drift should fail");
        let message = error.to_string();
        assert!(
            message.contains("replayed effective config does not match config lock"),
            "{message}"
        );
        assert!(message.contains("model = "), "{message}");
    }

    #[tokio::test]
    async fn lock_validation_rejects_codex_version_mismatch_by_default() {
        let sc = crate::session::tests::make_session_configuration_for_tests().await;
        let mut expected = sc.to_config_lockfile_toml().expect("lock should serialize");
        expected.codex_version = "older-version".to_string();
        let actual = sc.to_config_lockfile_toml().expect("lock should serialize");

        let error =
            validate_config_lock_replay(&expected, &actual, ConfigLockReplayOptions::default())
                .expect_err("version drift should fail");
        let message = error.to_string();
        assert!(
            message.contains("config lock Codex version mismatch"),
            "{message}"
        );
        assert!(
            message.contains("debug.config_lockfile.allow_codex_version_mismatch=true"),
            "{message}"
        );
    }

    #[tokio::test]
    async fn lock_validation_can_ignore_codex_version_mismatch() {
        let sc = crate::session::tests::make_session_configuration_for_tests().await;
        let mut expected = sc.to_config_lockfile_toml().expect("lock should serialize");
        expected.codex_version = "older-version".to_string();
        let actual = sc.to_config_lockfile_toml().expect("lock should serialize");

        validate_config_lock_replay(
            &expected,
            &actual,
            ConfigLockReplayOptions {
                allow_codex_version_mismatch: true,
            },
        )
        .expect("version drift should be ignored");
    }
}
