//! End-to-end Action Receipt on real hardware.
//!
//! ```text
//! cargo run -p jcp-action-receipt --example end_to_end -- /tmp/action.hex
//! ```
//!
//! Implements §5 step 6 of the blueprint: **one agent action, under a real
//! delegated grant, with energy read off this host's own counters, sealed into
//! an AR-1 receipt that a third party verifies from the published spec alone.**
//!
//! Only the workload is a stand-in, so the example runs anywhere. Everything
//! around it is the real machinery:
//!
//! - the grant is **really issued** and **really attenuated**, and amplification
//!   is really refused;
//! - the authorisation is a **real `decide` call** against a real budget, and
//!   the receipt records the verdict that call returned. It is decided before
//!   the work runs, so the cost it debits is the action's estimate
//!   ([`authorised_cost`], `Estimator`) — the work's reading is step 3's;
//! - the joules are **metered**, and the span's provenance is carried through
//!   verbatim: `HwShunt` only when every record the meter returned is a
//!   hardware reading. Where the host has no live counter — or the span's CPU
//!   counter held — the meter returns its `Estimator` record, and this example
//!   says so rather than inventing `HwShunt`;
//! - the tier is stamped from what is **actually running**. This is in-process
//!   with no isolation boundary crossed, so it is `S0`. Claiming `S5` without a
//!   microVM is exactly the overreach the ladder exists to prevent.

use ed25519_dalek::SigningKey;
use jcp_action_receipt::{ActionReceipt, Effect, EffectClass, Egress, EgressClass, verify};
use jcp_grant::{attenuate, issue};
use jcp_receipt as authority;
use jcp_runtime::Runtime;
use jcp_schema::{
    Capability, ContentId, Did, Energy, Frame, FrameKind, Grant, Trust, Verdict,
};
use sandbox_meter::{DeviceEnergy, PowerMeter, Receipt as WorkReceipt};
use sandbox_schema::Tier;

const STEWARD: &str = "did:example:ar-e2e";

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let out = std::env::args().nth(1).unwrap_or_else(|| "action.hex".into());

    // ── 1. A real grant, really delegated ────────────────────────────
    let issuer = SigningKey::from_bytes(&[11u8; 32]);
    let agent = SigningKey::from_bytes(&[22u8; 32]);
    let subagent = SigningKey::from_bytes(&[33u8; 32]);
    let agent_did = Did::from_verifying_key(&agent.verifying_key());
    let sub_did = Did::from_verifying_key(&subagent.verifying_key());

    let resource = ContentId::of_bytes(b"resource/quarterly-report");
    let root = Grant {
        issuer: Did::from_verifying_key(&issuer.verifying_key()),
        subject: agent_did,
        capability: Capability::new(resource, ["read", "summarise"]),
        budget_uj: 50_000_000,
        budget_funds: None,
        caveats: Vec::new(),
        expiry: 0,
        parent: None,
        delegate_depth: None,
        nonce: [1u8; 16],
    };
    let sg = issue(&issuer, root.clone())?;

    // Strictly narrower: read only, one fifth of the ceiling.
    let delegated = attenuate(
        &sg,
        &agent,
        sub_did,
        Capability::new(resource, ["read"]),
        10_000_000,
        0,
        [2u8; 16],
    )?;
    // And prove the runtime really refuses amplification, rather than asserting it.
    let amplified = attenuate(
        &sg,
        &agent,
        sub_did,
        Capability::new(resource, ["read", "delete"]),
        10_000_000,
        0,
        [3u8; 16],
    );
    assert!(amplified.is_err(), "amplification must be refused");
    println!("1. grant issued, attenuated to read-only — amplification refused: {}",
        amplified.unwrap_err());

    // ── 2. A real authorisation decision ─────────────────────────────
    let mut rt = Runtime::new();
    let frame = Frame {
        kind: FrameKind::ToolCall,
        trust: Trust::Control,
        grant_id: delegated.grant.id(),
        action: "read".into(),
        resource,
        payload_hash: ContentId::of_bytes(b"input/quarterly-report"),
        model: None,
    };
    let decision = rt.decide(&frame, &delegated, sub_did, authorised_cost(), 0);
    let verdict = match decision.verdict {
        Verdict::Allow => "allow",
        Verdict::Deny(_) => "deny",
    };
    // Seal the REAL authority receipt from the decision that just happened, and
    // take its content id from the bytes rather than naming a placeholder.
    let steward_key = SigningKey::from_bytes(&[44u8; 32]);
    let authority_env =
        authority::seal(&frame, &delegated.grant, &decision, &steward_key, STEWARD)?;
    let authority_core =
        authority::signed_core(&frame, &delegated.grant, &decision, STEWARD)?;
    let authority_id = ContentId::of_bytes(&authority_core);
    // Prove it verifies on its own terms before binding it.
    authority::verify(
        &frame,
        &delegated.grant,
        &decision,
        &authority_env,
        STEWARD,
        steward_key.verifying_key().as_bytes(),
    )?;
    println!(
        "2. decide() → {verdict}, {} µJ remaining; authority receipt sealed + verified, id {}",
        decision.budget_remaining_uj,
        &authority_id.to_hex()[..12]
    );

    // ── 3. Real work, really measured ────────────────────────────────
    let mut meter = PowerMeter::detect();
    let sources = meter.sources().join(",");
    let is_hw = meter.is_hardware();

    let span = meter.start();
    let mut acc: u64 = 0;
    for i in 0..40_000_000u64 {
        acc = acc.wrapping_add(i ^ (acc >> 7)).rotate_left(3);
    }
    let measurement = span.stop(&mut meter);
    std::hint::black_box(acc);

    let joules_uj = measurement.total_uj();
    // The span's own provenance, the weakest of its records. A hardware meter
    // still returns its estimator record for a span whose CPU counter held,
    // so `is_hardware()` says nothing about this span.
    let provenance = {
        use sandbox_meter::Provenance as P;
        let records = &measurement.devices;
        if records.is_empty() || records.iter().any(|d| d.provenance == P::Estimator) {
            "Estimator"
        } else if records.iter().all(|d| d.provenance == P::HwShunt && d.measured_uj.is_some()) {
            "HwShunt"
        } else {
            "ModelBased"
        }
    };
    println!(
        "3. work metered — {joules_uj} µJ [{provenance}] over {:.2}s via {sources}",
        measurement.wall.as_secs_f64()
    );
    if provenance != "HwShunt" {
        println!(
            "   note: this span was not a hardware reading; provenance is {provenance}, not HwShunt ({})",
            if is_hw { "its CPU counter held" } else { "no live energy counter here" }
        );
    }

    // Build the REAL work receipt from the devices the meter actually reported.
    // `Receipt::build` enforces the provenance/measured coupling itself, so a
    // mislabelled device is refused here rather than propagating into AR-1.
    let devices: Vec<DeviceEnergy> = measurement
        .devices
        .iter()
        .map(|d| DeviceEnergy {
            class: d.class,
            measured_uj: d.measured_uj,
            estimated_uj: d.estimated_uj,
            provenance: d.provenance,
        })
        .collect();
    let work = WorkReceipt::build(
        sandbox_schema::ContentId::of_bytes(b"unit/quarterly-report-summarise"),
        Tier::S0,
        devices,
        1,
        [7u8; 8],
    )?;
    work.validate()?;
    // The two families agree on BLAKE3 and disagree only on presentation:
    // sandbox renders `b3:<base64url>`, jcp carries raw 32 bytes. Re-addressing
    // the same canonical core with jcp's hasher yields the identical digest, so
    // the binding is exact rather than a hash of a hash.
    let work_id = ContentId::of_bytes(&work.canonical_core());
    debug_assert_eq!(
        work.content_id().as_str().trim_start_matches("b3:").len(),
        43,
        "sandbox content id should be b3:<base64url of 32 bytes>"
    );
    println!(
        "   work receipt sealed over {} metered device(s), id {}",
        measurement.devices.len(),
        &work_id.to_hex()[..12]
    );

    // ── 4. Seal the Action Receipt ───────────────────────────────────
    let receipt = ActionReceipt {
        closed_at: "2026-08-25T12:00:00Z".into(),
        grant_id: delegated.grant.id(),
        chain_ids: vec![sg.grant.id(), delegated.grant.id()],
        authority_receipt: authority_id,
        verdict: verdict.into(),
        attestation_id: ContentId::of_bytes(b"attest/e2e-local"),
        proof_cell_id: None,
        tier: "S0".into(),
        grounding: if is_hw { "hardware" } else { "software" }.into(),
        work_receipt: work_id,
        input_hash: ContentId::of_bytes(b"input/quarterly-report").to_hex(),
        output_hash: None,
        joules_uj,
        energy_provenance: provenance.into(),
        effect: Effect {
            // read-and-summarise changed nothing in the world
            class: EffectClass::None,
            target: resource,
            before: None,
            after: None,
            compensator: None,
            plan_receipt: None,
        },
        egress: Egress {
            // resolved entirely in this process
            class: EgressClass::None,
            bytes: 0,
            peer: None,
        },
        steward: STEWARD.into(),
    };

    let envelope = receipt.seal(&steward_key)?;
    println!("4. sealed — receipt id {}", receipt.id()?.to_hex());

    // ── 5. Verify it back, as a third party would ────────────────────
    let v = verify(&envelope, &steward_key.verifying_key(), STEWARD)?;
    assert_eq!(v.id, receipt.id()?);
    println!("5. verified from the envelope alone — {} byte canonical core", v.core.len());

    std::fs::write(&out, hex::encode(&envelope))?;
    println!();
    println!("wrote {out}");
    println!(
        "verify independently:\n  ar-verify {out} --pubkey {} --steward {STEWARD}",
        hex::encode(steward_key.verifying_key().as_bytes())
    );
    Ok(())
}

/// The cost the authorisation debits: decided before the work runs, it is
/// the action's estimate, 0.25 J, graded `Estimator` with no measured figure.
/// Sealed as a reading, the authority receipt would claim a meter read work
/// that had not yet happened; the joules a meter did read are the work
/// receipt's, and the action receipt's.
pub fn authorised_cost() -> Energy {
    Energy::estimator(250_000)
}