//! Config-approval request handlers: `RequestInitConfig` /
//! `RequestUpdateMetaInputs`, plus the shared submit helpers
//! (`submit_init_config` / `submit_merge_config_pr`).
//!
//! `submit_merge_config_pr` is called from the dashboard webhook handler
//! (`dashboard::webhook`) — agents no longer need an MCP tool for config
//! changes; opening a config PR on `agent-configs/<agent>` is enough to
//! trigger hive-c0re's webhook-driven queue path.

use std::sync::Arc;

use hive_core_agent_sock::Response;

use super::require_new_child;
use crate::coordinator::Coordinator;

/// `RequestInitConfig` — queue an `InitConfig` approval for an agent. The
/// `name` must be brand-new (absent from the topology) or already in the
/// caller's subtree; the requester is recorded as the new agent's parent (the
/// root requesting a new agent → a top-level agent, matching reconcile's
/// default).
pub(super) fn handle_request_init_config(
    coord: &Arc<Coordinator>,
    agent: &str,
    name: &str,
    description: Option<String>,
) -> Response {
    if let Some(err) = require_new_child(agent, name, "request_init_config for") {
        return err;
    }
    tracing::info!(%agent, %name, "request_init_config");
    match submit_init_config(coord, name, Some(agent), description) {
        Ok(_id) => Response::Ok,
        Err(e) => Response::Err {
            message: format!("{e:#}"),
        },
    }
}

/// `RequestUpdateMetaInputs` — queue an `UpdateMetaInputs` approval
/// carrying the JSON-encoded input list in `commit_ref` (no git commit
/// is involved; the field is the payload the approval handler decodes).
pub(super) fn handle_request_update_meta_inputs(
    coord: &Arc<Coordinator>,
    requester: &str,
    inputs: &[String],
    description: Option<&str>,
) -> Response {
    let label = if inputs.is_empty() {
        "all inputs".to_string()
    } else {
        inputs.join(", ")
    };
    tracing::info!(%requester, %label, "request_update_meta_inputs");
    let commit_ref = serde_json::to_string(inputs).unwrap_or_default();
    let id = match coord
        .approvals
        .submit_kind(
            requester,
            hive_sh4re::approvals::ApprovalKind::UpdateMetaInputs,
            &commit_ref,
            description,
            requester,
            None,
        )
        .map_err(|e| anyhow::anyhow!("{e:#}"))
    {
        Ok(id) => id,
        Err(e) => {
            return Response::Err {
                message: format!("queue update_meta_inputs approval: {e:#}"),
            };
        }
    };
    tracing::info!(%id, %label, "update_meta_inputs approval queued");
    coord.emit_approval_added(crate::coordinator::ApprovalAdded {
        id,
        agent: requester,
        approval_kind: "update_meta_inputs",
        sha_short: None,
        description: description.map(str::to_owned),
        pr_number: None,
    });
    Response::Ok
}

/// Submit-time half of the PR-merge flow: fetch the PR head sha from the
/// forge, queue the approval row, and emit the `approval_added` event so the
/// dashboard shows the pending card immediately.
///
/// The PR head sha is stored as `fetched_sha` on the approval row — the
/// "reviewed sha" the deploy's `MergeVerify` node drift-gates
/// against before doing anything irreversible. This does NOT fetch the commit
/// into the applied repo at submission time (that happens inside the approve
/// handler, step 2, after the drift check). No flake pre-flight either —
/// eval-verify happens at approval time too.
pub(crate) async fn submit_merge_config_pr(
    coord: &Arc<Coordinator>,
    agent: &str,
    pr_number: u64,
    description: Option<&str>,
    submitter: &str,
) -> anyhow::Result<i64> {
    let applied_dir = crate::paths::applied_dir(agent);
    if !applied_dir.join(".git").exists() {
        anyhow::bail!(
            "applied repo missing for agent '{agent}' (expected at {}) — \
             merge_config_pr requires the agent to be fully provisioned; \
             spawn the agent first (operator spawn) before opening config PRs",
            applied_dir.display()
        );
    }
    let repo = crate::forge::config_repo(agent);
    // Verify the PR is still open before queueing an approval that would
    // fail at approve time anyway (a closed/merged PR has no live head ref
    // for the drift gate to compare against).
    if !crate::forge::pr_is_open(&repo, pr_number)
        .await
        .map_err(|e| anyhow::anyhow!("check PR state for {agent} PR #{pr_number}: {e}"))?
    {
        anyhow::bail!(
            "PR #{pr_number} on {repo} is closed or already merged — \
             merge_config_pr requires an open PR"
        );
    }
    // Fetch the current PR head sha — becomes the "reviewed" sha.
    // Submitted together with the approval row (atomic single INSERT) so a
    // crash mid-submit cannot leave a stranded sha-less row.
    let sha = crate::forge::pr_head_sha(&repo, pr_number)
        .await
        .map_err(|e| anyhow::anyhow!("fetch PR head sha for {agent} PR #{pr_number}: {e}"))?;
    // Both the webhook (`synchronize`) and the poll fallback call this on
    // every PR update. If an approval for this PR is already pending, reconcile
    // it against the live head sha rather than blindly queuing another:
    //   - same sha → the PR hasn't moved, so this is a duplicate signal — no-op.
    //   - drifted sha → the reviewed head is stale. Don't mutate the
    //     pending row in place (that races a concurrent approve); cancel it and
    //     fall through to queue a FRESH approval pinned to the new head.
    if let Some((old_id, old_sha)) = coord.approvals.pending_merge_config_pr(agent, pr_number)? {
        if old_sha.as_deref() == Some(sha.as_str()) {
            return Ok(old_id);
        }
        let cancelled = coord
            .approvals
            .mark_cancelled(old_id, "config PR updated — superseded by a fresh approval")
            .map_err(|e| anyhow::anyhow!("cancel superseded merge_config_pr approval: {e:#}"))?;
        coord.emit_approval_resolved(crate::coordinator::ApprovalResolved {
            id: old_id,
            agent,
            approval_kind: "merge_config_pr",
            sha_short: old_sha.map(|s| s[..s.len().min(12)].to_owned()),
            status: "cancelled",
            note: Some("PR head moved; superseded by a fresh approval".to_owned()),
            description: cancelled.description,
        });
    }
    let id = coord
        .approvals
        .submit_kind(
            agent,
            hive_sh4re::approvals::ApprovalKind::MergeConfigPr,
            &pr_number.to_string(),
            description,
            submitter,
            Some(&sha), // atomic: sha inserted with the row, not in a separate UPDATE
        )
        .map_err(|e| anyhow::anyhow!("queue merge_config_pr approval row: {e:#}"))?;
    let sha_short = sha[..sha.len().min(12)].to_owned();
    coord.emit_approval_added(crate::coordinator::ApprovalAdded {
        id,
        agent,
        approval_kind: "merge_config_pr",
        sha_short: Some(sha_short),
        description: description.map(str::to_owned),
        pr_number: Some(pr_number),
    });
    Ok(id)
}

/// Queue an `InitConfig` approval for a brand-new agent whose config repo
/// does not yet exist. Shared between the manager and agent sockets.
///
/// `parent`, when `Some`, is the agent that will own the new child once
/// the operator approves: it is stashed in the approval's `commit_ref`
/// field (unused for `InitConfig` otherwise — same pattern
/// `UpdateMetaInputs` uses to carry its inputs JSON) and consumed in
/// `run_approval_init_config` to write the `child -> parent` topology
/// edge. Callers pass the requesting agent, so the requester becomes the
/// new agent's parent (the root requesting a new agent → a top-level agent,
/// matching `topology::reconcile`'s default). `None` writes no explicit
/// edge (reconcile-default placement) — retained for that fallback.
pub(crate) fn submit_init_config(
    coord: &Arc<Coordinator>,
    name: &str,
    parent: Option<&str>,
    description: Option<String>,
) -> anyhow::Result<i64> {
    let agent = hive_types::Ident::parse(name)
        .map_err(|e| anyhow::anyhow!("invalid agent name {name:?}: {e}"))?;
    let proposed_dir = crate::coordinator::Coordinator::agent_proposed_dir(&agent);
    if proposed_dir.join(".git").exists() {
        anyhow::bail!(
            "proposed config repo for '{name}' already exists at {} - \
             nothing to init; config changes go through a forge PR on \
             agent-configs/{name}",
            proposed_dir.display()
        );
    }
    let id = coord
        .approvals
        .submit_kind(
            name,
            hive_sh4re::approvals::ApprovalKind::InitConfig,
            parent.unwrap_or(""),
            description.as_deref(),
            // `parent` is the requesting agent (becomes the new child's
            // parent); it's also the submitter the approval events route
            // back to. No declared parent = operator-initiated path.
            parent.unwrap_or("operator"),
            None, // no sha for InitConfig
        )
        .map_err(|e| anyhow::anyhow!("queue approval row: {e:#}"))?;
    tracing::info!(%id, %name, "init_config approval queued");
    coord.emit_approval_added(crate::coordinator::ApprovalAdded {
        id,
        agent: name,
        approval_kind: "init_config",
        sha_short: None,
        description,
        pr_number: None,
    });
    Ok(id)
}