//! gsh — Governed Shell (machine mode)
//!
//! GCAP-SPEC-SHELLBOUND-SDK-0001
//!
//! Usage:
//!   gsh --exec "echo hello"
//!   gsh --exec "hcloud server list" --json
//!
//! Environment:
//!   GSAP_BROKER_URL    http://fastapi-gsap:8000
//!   GSAP_AGENT_DID     did:web:bxnet.../agent/platform-ops
//!   GSAP_TOKEN         Bearer token for broker auth (optional)
//!   GSAP_CORPUS_CID    Corpus entry CID (optional)

use anyhow::{bail, Context, Result};
use clap::Parser;
use reqwest::blocking::Client;
use serde::{Deserialize, Serialize};
use sha2::{Digest, Sha256};
use std::process;
use std::time::Duration;
use uuid::Uuid;

#[derive(Parser)]
#[command(name = "gsh", about = "Governed shell — GCAP machine mode")]
struct Args {
    /// Command to execute (via sh -c)
    #[arg(long, short = 'e')]
    exec: String,

    /// Override broker URL (default: $GSAP_BROKER_URL)
    #[arg(long)]
    broker_url: Option<String>,

    /// Override agent DID (default: $GSAP_AGENT_DID)
    #[arg(long)]
    agent_did: Option<String>,

    /// Operation label (default: shell:exec)
    #[arg(long, default_value = "shell:exec")]
    operation: String,

    /// JSON output with CIDs
    #[arg(long)]
    json: bool,

    /// Request AC but skip execution
    #[arg(long)]
    dry_run: bool,
}

// ── GSAP broker request/response types ──────────────────────

#[derive(Serialize)]
struct AcRequest {
    driver_id: String,
    playbook: String,
    corpus_entry_cid: String,
    parameters_cid: String,
    accord_template: String,
}

#[derive(Deserialize)]
struct AcResponse {
    status: Option<String>,
    authorization_context: Option<AcContext>,
}

#[derive(Deserialize)]
struct AcContext {
    context_id: String,
}

#[derive(Serialize)]
struct CrRequest {
    context_id: String,
    outcome: String,
    completed_at: String,
    chronicle_evidence: CrEvidence,
    behavioral_attestation: CrAttestation,
    ffc: serde_json::Value,
    signature: serde_json::Value,
}

#[derive(Serialize)]
struct CrEvidence {
    events: Vec<String>,
    merkle_root: String,
}

#[derive(Serialize)]
struct CrAttestation {
    status: String,
}

#[derive(Deserialize)]
struct CrResponse {
    receipt_id: Option<String>,
    chronicle_event_cid: Option<String>,
}

#[derive(Serialize)]
struct GshOutput {
    exit_code: i32,
    stdout: String,
    stderr: String,
    ac_id: String,
    cr_id: String,
    chronicle_cid: String,
    command_hash: String,
    run_id: String,
}

// ── Main ────────────────────────────────────────────────────

fn main() {
    let args = Args::parse();
    match run(args) {
        Ok(code) => process::exit(code),
        Err(e) => {
            eprintln!("gsh: {:#}", e);
            process::exit(125);
        }
    }
}

fn run(args: Args) -> Result<i32> {
    let broker_url = args
        .broker_url
        .or_else(|| std::env::var("GSAP_BROKER_URL").ok())
        .context("GSAP_BROKER_URL not set")?;

    let agent_did = args
        .agent_did
        .or_else(|| std::env::var("GSAP_AGENT_DID").ok())
        .context("GSAP_AGENT_DID not set")?;

    let corpus_cid =
        std::env::var("GSAP_CORPUS_CID").unwrap_or_else(|_| "sha256:ungoverned".into());

    let token = std::env::var("GSAP_TOKEN").ok();
    let run_id = Uuid::new_v4().to_string();

    // Hash the command — the broker sees WHAT will be executed
    let command_hash = format!(
        "sha256:{}",
        hex::encode(Sha256::digest(args.exec.as_bytes()))
    );

    // Build client
    let mut headers = reqwest::header::HeaderMap::new();
    if let Some(ref tok) = token {
        headers.insert(
            "Authorization",
            format!("Bearer {}", tok)
                .parse()
                .context("Invalid GSAP_TOKEN")?,
        );
    }

    let client = Client::builder()
        .timeout(Duration::from_secs(30))
        .default_headers(headers)
        .build()
        .context("HTTP client build failed")?;

    // ── Request AC ──────────────────────────────────────────

    eprintln!("gsh: requesting AC for '{}'", args.exec);

    let ac_resp = client
        .post(format!(
            "{}/governance/authorize/",
            broker_url.trim_end_matches('/')
        ))
        .json(&AcRequest {
            driver_id: "keycloak".into(),
            playbook: format!("{}:{}", args.operation, &command_hash[..20]),
            corpus_entry_cid: corpus_cid,
            parameters_cid: command_hash.clone(),
            accord_template: "shell-exec".into(),
        })
        .send()
        .context("Failed to reach GSAP broker")?;

    if !ac_resp.status().is_success() {
        let status = ac_resp.status();
        let body = ac_resp.text().unwrap_or_default();
        bail!("AC denied: {} — {}", status, body);
    }

    let ac: AcResponse = ac_resp.json().context("Invalid AC response")?;

    let ac_id = ac
        .authorization_context
        .as_ref()
        .map(|c| c.context_id.clone())
        .unwrap_or_default();

    if ac_id.is_empty() {
        bail!(
            "AC not authorized: status={:?}",
            ac.status
        );
    }

    eprintln!("gsh: AC issued — {}", &ac_id[..8.min(ac_id.len())]);

    if args.dry_run {
        eprintln!("gsh: dry-run — skipping execution");
        if args.json {
            println!(
                "{}",
                serde_json::to_string_pretty(&GshOutput {
                    exit_code: 0,
                    stdout: String::new(),
                    stderr: String::new(),
                    ac_id,
                    cr_id: String::new(),
                    chronicle_cid: String::new(),
                    command_hash,
                    run_id,
                })?
            );
        }
        return Ok(0);
    }

    // ── Execute ─────────────────────────────────────────────

    let output = process::Command::new("sh")
        .arg("-c")
        .arg(&args.exec)
        .output()
        .context("Failed to execute command")?;

    let exit_code = output.status.code().unwrap_or(1);
    let stdout_str = String::from_utf8_lossy(&output.stdout).to_string();
    let stderr_str = String::from_utf8_lossy(&output.stderr).to_string();

    // ── Post CR ─────────────────────────────────────────────

    let outcome = if exit_code == 0 {
        "completed"
    } else {
        "failed"
    };

    let now = chrono::Utc::now().to_rfc3339();

    let (cr_id, chronicle_cid) = match client
        .post(format!(
            "{}/governance/complete/",
            broker_url.trim_end_matches('/')
        ))
        .json(&CrRequest {
            context_id: ac_id.clone(),
            outcome: outcome.into(),
            completed_at: now,
            chronicle_evidence: CrEvidence {
                events: vec![],
                merkle_root: String::new(),
            },
            behavioral_attestation: CrAttestation {
                status: "unavailable".into(),
            },
            ffc: serde_json::json!({"did": "did:web:guildhouse.dev"}),
            signature: serde_json::json!({"value": "gsh-machine-mode"}),
        })
        .send()
    {
        Ok(resp) if resp.status().is_success() => {
            let cr: CrResponse = resp.json().unwrap_or(CrResponse {
                receipt_id: None,
                chronicle_event_cid: None,
            });
            (
                cr.receipt_id.unwrap_or_default(),
                cr.chronicle_event_cid.unwrap_or_default(),
            )
        }
        Ok(resp) => {
            eprintln!("gsh: CR failed: {}", resp.status());
            (String::new(), String::new())
        }
        Err(e) => {
            eprintln!("gsh: CR error: {}", e);
            (String::new(), String::new())
        }
    };

    // ── Output ──────────────────────────────────────────────

    if args.json {
        println!(
            "{}",
            serde_json::to_string_pretty(&GshOutput {
                exit_code,
                stdout: stdout_str,
                stderr: stderr_str,
                ac_id,
                cr_id,
                chronicle_cid,
                command_hash,
                run_id,
            })?
        );
    } else {
        print!("{}", stdout_str);
        eprint!("{}", stderr_str);
        if !chronicle_cid.is_empty() {
            eprintln!("gsh: CID {}", &chronicle_cid[..40.min(chronicle_cid.len())]);
        }
    }

    Ok(exit_code)
}