//! System-prompt renderer. Single `prompts/system.md`, a Jinja template rendered
//! through `hive-template` with an if/else block for the config-repo paragraphs;
//! this module builds its variables and assembles the final prompt. The template
//! rules and variables are in
//! `docs/4-implementation/turn-loop/claude-invocation.md::On-boot files` (`claude-system-prompt.md`).

use std::path::{Path, PathBuf};
use std::time::Duration;

use anyhow::{Context, Result};
use swarm_queue_client::operator_profiles::{self, OperatorProfile};

/// How long [`write_system_prompt`] waits for the operator list before
/// rendering without it.
const OPERATORS_TIMEOUT: Duration = Duration::from_secs(5);

/// Assemble the system prompt for a given label + optional hive /
/// swarm display names + the swarm's operators. Pure function — no I/O. Splits out from
/// [`write_system_prompt`] so the template rendering is unit-testable
/// in isolation. The caller supplies the template body so tests can pass an
/// inline fixture and production reads it once at harness startup via
/// [`hive_sh4re::assets::prompt_template`]
/// (`$HIVE_ASSETS_DIR/prompts/system.md`). The template rules and
/// variables are documented in
/// `docs/4-implementation/turn-loop/claude-invocation.md::On-boot files` (`claude-system-prompt.md`).
#[must_use]
pub fn render(
    template: &str,
    label: &str,
    archetype: Option<&str>,
    hive_name: Option<&str>,
    swarm_name: Option<&str>,
    docs_dir: Option<&str>,
    operators: &[OperatorProfile],
) -> String {
    let hive_identity = hive_name
        .filter(|n| !n.is_empty())
        .map_or(String::new(), |n| format!(" on hive `{n}`"));
    let swarm_identity = swarm_name
        .filter(|n| !n.is_empty())
        .map_or(String::new(), |n| format!(" in swarm `{n}`"));
    let context = serde_json::json!({
        "label": label,
        "qualified_label": crate::identity::qualify(label),
        "hive_identity": hive_identity,
        "swarm_identity": swarm_identity,
        "operators": operators_line(operators),
        // Absent for a custom agent, which has a config repo of its own.
        "archetype": archetype.filter(|a| !a.is_empty()),
    });
    let rendered = match hive_template::render(template, &context) {
        Ok(text) => text,
        Err(why) => {
            tracing::error!(%why, "prompt: the system prompt template does not render; using it as written");
            template.to_owned()
        }
    };
    // When the reference docs are mounted in-container (`services.hyperhive.agent.docs.enable`
    // wires `HIVE_DOCS_DIR` + `claude --add-dir`), append a single pointer
    // sentence so the agent knows they exist. Additive: it doesn't replace the
    // agent's own memory/project instructions. Absent env → no change.
    match docs_dir.filter(|d| !d.is_empty()) {
        Some(dir) => format!(
            "{rendered}\n\nThe hyperhive reference docs (the repo `docs/` tree \
             describing this live system) are mounted read-only at `{dir}` — read \
             them (start at the index, then the topic file for the area you're \
             touching) rather than guessing.\n"
        ),
        None => rendered,
    }
}

/// The `{operators}` substitution: a paragraph naming each operator, with their
/// pronouns where set, or nothing when there are none.
fn operators_line(operators: &[OperatorProfile]) -> String {
    if operators.is_empty() {
        return String::new();
    }
    let names: Vec<String> = operators
        .iter()
        .map(|o| match &o.pronouns {
            Some(pronouns) => format!("{} ({pronouns})", o.name),
            None => o.name.clone(),
        })
        .collect();
    format!("\n\nOperators: {}.", names.join(", "))
}

/// The swarm's operators, or none when the operator-profile bucket cannot be
/// read within [`OPERATORS_TIMEOUT`]: the prompt then reads as it does with no
/// operator list.
async fn operators() -> Vec<OperatorProfile> {
    within_timeout(OPERATORS_TIMEOUT, read_operators()).await
}

/// One read of the operator list over this agent's queue connection.
async fn read_operators()
-> std::result::Result<Vec<OperatorProfile>, Box<dyn std::error::Error + Send + Sync>> {
    let client = crate::swarm_queue::client().await;
    swarm_queue_client::ensure_connected(&client)?;
    match operator_profiles::read(&client).await? {
        operator_profiles::Read::Current(operators) => Ok(operators),
        operator_profiles::Read::NoBucket => {
            Err("the operator-profiles bucket does not answer".into())
        }
    }
}

/// `read`'s profiles, or none when it fails or outlasts `timeout`.
async fn within_timeout<E: std::fmt::Display>(
    timeout: Duration,
    read: impl Future<Output = std::result::Result<Vec<OperatorProfile>, E>>,
) -> Vec<OperatorProfile> {
    match tokio::time::timeout(timeout, read).await {
        Ok(Ok(operators)) => operators,
        Ok(Err(e)) => {
            tracing::warn!(error = %e, "prompt: operator profiles unreadable; rendering without them");
            Vec::new()
        }
        Err(_) => {
            tracing::warn!(
                timeout_s = timeout.as_secs(),
                "prompt: no operator profiles within the timeout; rendering without them"
            );
            Vec::new()
        }
    }
}

/// Write the assembled prompt to a stable path next to the harness
/// socket and return the path. The Rust harness passes this path to
/// `claude --system-prompt-file` so the per-turn prompts only carry
/// the role + tools instructions in the system slot; per-turn prompts
/// become much smaller (just the wake-message body).
///
/// # Errors
///
/// Returns an error if the system prompt file cannot be written.
pub async fn write_system_prompt(_socket: &Path, label: &str) -> Result<PathBuf> {
    let parent = crate::paths::config_dir();
    tokio::fs::create_dir_all(&parent).await.ok();
    let template_path = hive_sh4re::assets::prompt_template();
    let template = tokio::fs::read_to_string(&template_path)
        .await
        .with_context(|| {
            format!(
                "read claude system prompt template from {}",
                template_path.display()
            )
        })?;
    // Surface hive + swarm display names in the prompt opener when
    // configured. Both `None` falls back to the non-identity wording
    // verbatim (single-hive deployments see no diff).
    let hive_name = crate::identity::hive_name();
    let swarm_name = crate::identity::swarm_name();
    // `services.hyperhive.agent.docs.enable` sets HIVE_DOCS_DIR (and the harness passes it to
    // claude via `--add-dir`); when present, render() appends a pointer line.
    let docs_dir = std::env::var("HIVE_DOCS_DIR")
        .ok()
        .filter(|d| !d.is_empty());
    // The meta flake sets HIVE_ARCHETYPE on an agent built from an archetype,
    // which has no config repo of its own.
    let archetype = std::env::var("HIVE_ARCHETYPE").ok();
    let body = render(
        &template,
        label,
        archetype.as_deref(),
        hive_name.as_deref(),
        swarm_name.as_deref(),
        docs_dir.as_deref(),
        &operators().await,
    );
    let path = parent.join("claude-system-prompt.md");
    tokio::fs::write(&path, body).await?;
    tracing::info!(path = %path.display(), "wrote claude system prompt");
    Ok(path)
}

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

    // The production template lives at `$HIVE_ASSETS_DIR/prompts/system.md`
    // and is loaded at runtime. The unit tests below want to assert
    // against the actual production wording (so the renderer + tool
    // surface stay honest), so they resolve the same path at test
    // runtime via two fallbacks:
    //   1. `$HIVE_ASSETS_DIR/prompts/system.md` — the runtime contract
    //      production uses. The flake's `checks.cargo-test` derivation
    //      sets this to the `hyperhive-assets` output so `cargo test`
    //      inside the nix sandbox finds the file without needing
    //      `prompts/` in the cargo source tree. `packages.default`
    //      explicitly does NOT carry the assets dep, so a prompt edit
    //      doesn't bust the binary derivation — only this test check.
    //   2. `env!("CARGO_MANIFEST_DIR")/prompts/system.md` — for plain
    //      `cargo test --workspace` from a checked-out repo where the
    //      env var isn't set; `env!` is a compile-time string lookup,
    //      no file open at compile, so this still doesn't pull
    //      `prompts/` into the build hash.
    // The combined effect is that the flake's `cleanSrc` no longer
    // unions `./hive-agent/prompts` — tweaks to system.md don't bust
    // the cargo cache anymore.
    static PRODUCTION_TEMPLATE: LazyLock<String> = LazyLock::new(|| {
        let path = match std::env::var("HIVE_ASSETS_DIR") {
            Ok(v) if !v.is_empty() => format!("{v}/prompts/system.md"),
            _ => concat!(env!("CARGO_MANIFEST_DIR"), "/prompts/system.md").to_owned(),
        };
        std::fs::read_to_string(&path)
            .unwrap_or_else(|e| panic!("read production prompt template at {path}: {e}"))
    });

    #[test]
    fn render_substitutes_label_and_names_no_operator_pronouns() {
        // Real template's first agent line.
        let rendered = render(&PRODUCTION_TEMPLATE, "alice", None, None, None, None, &[]);
        assert!(rendered.contains("hyperhive agent `alice`"));
        assert!(rendered.contains("say \"the operator\""));
        assert!(!rendered.contains("pronoun"));
        assert!(!rendered.contains("{label}"));
        assert!(!rendered.contains("{operator_pronouns}"));
    }

    #[test]
    fn render_leaves_no_template_syntax_in_output() {
        // No raw template tag should survive into the rendered prompt.
        let rendered = render(&PRODUCTION_TEMPLATE, "alice", None, None, None, None, &[]);
        assert!(!rendered.contains("{{"));
        assert!(!rendered.contains("{%"));
        // The guidance the tool schemas cannot give still appears.
        assert!(rendered.contains("mcp__matrix__send_dm"));
        assert!(rendered.contains("ending the turn"));
    }

    #[test]
    fn render_uses_agent_opener() {
        let rendered = render(&PRODUCTION_TEMPLATE, "alice", None, None, None, None, &[]);
        assert!(rendered.starts_with("You are hyperhive agent"));
    }

    #[test]
    fn render_points_agents_at_the_work_dir() {
        let rendered = render(&PRODUCTION_TEMPLATE, "alice", None, None, None, None, &[]);
        assert!(rendered.contains("`/agents/alice/work/`"), "{rendered}");
    }

    const CONFIG_FIXTURE: &str = "\
shared
{% if not archetype %}
open a PR on agent-configs
{% else %}
built from `{{ archetype }}`, no config repo
{% endif %}
";

    /// A custom agent gets the config-repo lines, an archetype agent the
    /// archetype lines with its name, and an empty name is a custom agent.
    #[test]
    fn the_config_block_follows_the_archetype() {
        for custom in [None, Some("")] {
            let picked = render(CONFIG_FIXTURE, "alice", custom, None, None, None, &[]);
            assert_eq!(picked, "shared\nopen a PR on agent-configs\n");
        }
        let picked = render(
            CONFIG_FIXTURE,
            "alice",
            Some("android-dev"),
            None,
            None,
            None,
            &[],
        );
        assert_eq!(picked, "shared\nbuilt from `android-dev`, no config repo\n");
    }

    #[test]
    fn the_production_prompt_keeps_no_template_syntax() {
        for archetype in [None, Some("reviewer")] {
            let rendered = render(
                &PRODUCTION_TEMPLATE,
                "alice",
                archetype,
                None,
                None,
                None,
                &[],
            );
            for left in ["{{", "{%", "<!-- config:", "<!-- /config:", "{archetype}"] {
                assert!(!rendered.contains(left), "{left} left in:\n{rendered}");
            }
        }
    }

    // Inline fixture for the {{ hive_identity }} / {{ swarm_identity }}
    // variables. Cargo's `cargo test` resolves `PRODUCTION_TEMPLATE`
    // against `$HIVE_ASSETS_DIR/prompts/system.md`, which the flake
    // builds at derivation time — a fresh placeholder added on the
    // source side isn't in the shipped asset until the flake rebuilds,
    // so PRODUCTION_TEMPLATE can't be the fixture here. The string
    // below carries just enough of the opener shape to exercise the
    // substitution logic; nothing here depends on the production
    // template's config block.
    const IDENTITY_FIXTURE: &str = "\
You are hyperhive agent `{{ label }}` (qualified: `{{ qualified_label }}`){{ hive_identity }}{{ swarm_identity }} in a multi-agent system.
";

    #[test]
    fn render_substitutes_hive_identity_when_set() {
        let rendered = render(
            IDENTITY_FIXTURE,
            "alice",
            None,
            Some("pr1ma"),
            None,
            None,
            &[],
        );
        assert!(rendered.contains("on hive `pr1ma`"), "{rendered}");
        // swarm clause stays absent when only hive is set.
        assert!(!rendered.contains("in swarm"));
        // No raw placeholder leaks.
        assert!(!rendered.contains("{hive_identity}"));
        assert!(!rendered.contains("{swarm_identity}"));
    }

    #[test]
    fn render_substitutes_swarm_identity_when_set() {
        let rendered = render(
            IDENTITY_FIXTURE,
            "ruth",
            None,
            None,
            Some("constellat1on"),
            None,
            &[],
        );
        assert!(rendered.contains("in swarm `constellat1on`"));
        assert!(!rendered.contains("on hive"));
    }

    #[test]
    fn render_substitutes_both_when_both_set() {
        let rendered = render(
            IDENTITY_FIXTURE,
            "iris",
            None,
            Some("pr1ma"),
            Some("constellat1on"),
            None,
            &[],
        );
        // Order: hive then swarm, both inline before "in a multi-agent
        // system" — keeps the opener grammar intact.
        assert!(rendered.contains("on hive `pr1ma` in swarm `constellat1on`"));
    }

    #[test]
    fn render_omits_identity_when_unset() {
        // None / None must round-trip the non-identity opener verbatim
        // — single-hive deployments see zero diff.
        let rendered = render(IDENTITY_FIXTURE, "alice", None, None, None, None, &[]);
        assert!(!rendered.contains("on hive"));
        assert!(!rendered.contains("in swarm"));
        assert!(!rendered.contains("{hive_identity}"));
        assert!(!rendered.contains("{swarm_identity}"));
    }

    #[test]
    fn render_treats_empty_identity_as_none() {
        // Defensive: an env var set to empty string round-trips
        // through `identity::hive_name()` as None (the accessor
        // filters empty), but `render` should still no-op on a
        // direct `Some("")` from a test fixture or a future caller.
        let rendered = render(
            IDENTITY_FIXTURE,
            "alice",
            None,
            Some(""),
            Some(""),
            None,
            &[],
        );
        assert!(!rendered.contains("on hive"));
        assert!(!rendered.contains("in swarm"));
    }

    #[test]
    fn render_appends_docs_pointer_when_docs_dir_set() {
        let rendered = render(
            &PRODUCTION_TEMPLATE,
            "alice",
            None,
            None,
            None,
            Some("/run/hive-docs"),
            &[],
        );
        // Key on a phrase unique to the pointer sentence — "reference docs"
        // alone also appears in the /knowledge blurb of the base template.
        assert!(
            rendered.contains("mounted read-only at `/run/hive-docs`"),
            "expected docs pointer sentence with the dir:\n{rendered}"
        );
    }

    #[test]
    fn render_no_docs_pointer_when_docs_dir_absent_or_empty() {
        for docs in [None, Some("")] {
            let rendered = render(&PRODUCTION_TEMPLATE, "alice", None, None, None, docs, &[]);
            assert!(
                !rendered.contains("mounted read-only at"),
                "docs pointer must not appear for {docs:?}:\n{rendered}"
            );
        }
    }

    fn operator(name: &str, pronouns: Option<&str>) -> OperatorProfile {
        OperatorProfile {
            name: name.to_owned(),
            pronouns: pronouns.map(str::to_owned),
        }
    }

    const OPERATORS_FIXTURE: &str = "say \"the operator\".{{ operators }}\n\nnext paragraph\n";

    #[test]
    fn render_lists_operators_with_their_pronouns() {
        let operators = [operator("mara", Some("she/her")), operator("sol", None)];
        let rendered = render(
            OPERATORS_FIXTURE,
            "alice",
            None,
            None,
            None,
            None,
            &operators,
        );
        assert_eq!(
            rendered,
            "say \"the operator\".\n\nOperators: mara (she/her), sol.\n\nnext paragraph\n"
        );
        let rendered = render(
            &PRODUCTION_TEMPLATE,
            "alice",
            None,
            None,
            None,
            None,
            &operators,
        );
        assert!(
            rendered.contains("Operators: mara (she/her), sol."),
            "{rendered}"
        );
    }

    /// No operators renders the template as it reads without the placeholder,
    /// byte for byte.
    #[test]
    fn render_with_no_operators_is_the_template_without_the_placeholder() {
        let rendered = render(OPERATORS_FIXTURE, "alice", None, None, None, None, &[]);
        assert_eq!(rendered, "say \"the operator\".\n\nnext paragraph\n");
        assert!(PRODUCTION_TEMPLATE.contains("{{ operators }}"));
        assert_eq!(
            render(&PRODUCTION_TEMPLATE, "alice", None, None, None, None, &[]),
            render(
                &PRODUCTION_TEMPLATE.replace("{{ operators }}", ""),
                "alice",
                None,
                None,
                None,
                None,
                &[]
            )
        );
    }

    /// An unreachable or failing bucket reads as no operators, so the prompt
    /// renders as it does with none.
    #[tokio::test(start_paused = true)]
    async fn an_unread_operator_list_is_empty() {
        let hangs = std::future::pending::<std::result::Result<Vec<OperatorProfile>, String>>();
        let start = tokio::time::Instant::now();
        assert_eq!(within_timeout(OPERATORS_TIMEOUT, hangs).await, []);
        assert!(
            start.elapsed() < OPERATORS_TIMEOUT * 2,
            "{:?}",
            start.elapsed()
        );
        let fails = async { Err::<Vec<OperatorProfile>, _>("no bucket".to_owned()) };
        assert_eq!(within_timeout(OPERATORS_TIMEOUT, fails).await, []);
        // Control: a read that answers in time is what comes back.
        let answers = async { Ok::<_, String>(vec![operator("mara", Some("she/her"))]) };
        assert_eq!(
            within_timeout(OPERATORS_TIMEOUT, answers).await,
            [operator("mara", Some("she/her"))]
        );
    }
}