//! `spectra init` and `spectra identity`: the owner and the instance

//! (spec §8.3, §9.5). The owner proves possession of their identity by

//! signing with it; Spectra never holds the owner's secret key.

use super::{ui, Ctx};

use anyhow::{bail, Context, Result};

use oxy_core::identity::Identity;

use spectra_core::keys::KeyPair;

use spectra_core::ledger::Ledger;

use spectra_core::principals::{identity_payload, signed_event, Principals};

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

/// The owner's `OXY_HOME`: `--owner-home`, else `[owner] home` in

/// spectra.toml, else oxy's own default.

pub fn owner_home(ctx: &Ctx, flag: Option<PathBuf>) -> PathBuf {

    flag.or_else(|| ctx.config_owner_home()).unwrap_or_else(oxy_core::repo::default_home)

}

pub async fn init(ctx: &Ctx, owner_home_flag: Option<PathBuf>, name: Option<String>) -> Result<i32> {

    let data = &ctx.data;

    let db = data.join("spectra.db");

    if db.exists() {

        bail!("{} already holds a Spectra (spectra identity show)", data.display());

    }

    let home = owner_home(ctx, owner_home_flag);

    let owner = KeyPair::load_home(&home).with_context(|| {

        format!("the owner signs with their own identity: none usable in {} (oxy identity create, or --owner-home)", home.display())

    })?;

    std::fs::create_dir_all(data)?;

    #[cfg(unix)]

    {

        use std::os::unix::fs::PermissionsExt;

        std::fs::set_permissions(data, std::fs::Permissions::from_mode(0o700))?;

    }

    let name = name.unwrap_or_else(hostname);

    let instance = KeyPair::instance(data, &name)?;

    let ledger = Ledger::open(&db, Some(instance.clone())).await?;

    ledger

        .append(vec![

            signed_event(&owner, "human", "identity.owner", identity_payload(&owner.identity)),

            signed_event(&instance, "system", "identity.instance", identity_payload(&instance.identity)),

        ])

        .await?;

    ledger.checkpoint().await?;

    let home_s = home.display().to_string();

    std::fs::write(

        data.join("spectra.toml"),

        format!("# Spectra's configuration (spec §22.1).\n\n[owner]\nkey = \"{}\"\nhome = {}\n", owner.key.to_hex(), toml_str(&home_s)),

    )?;

    println!("{} {}  {}", ui::done("Initialised"), ui::subject("Spectra"), ui::path(data.display()));

    println!("{}", ui::kv("owner", format!("{}{}{}", ui::author(&owner.identity.name), ui::sep(), ui::hash(owner.key.short(12)))));

    println!("{}", ui::kv("instance", format!("{}{}{}", name, ui::sep(), ui::hash(instance.key.short(12)))));

    println!("{}", ui::kv("ledger", format!("{}{}", ui::path(db.display()), ui::dim(" (verified with spectra admin verify)"))));

    println!();

    println!("  {} {}", ui::note(), ui::dim("so that checkpoints are verifiably from your machine, delegate to the instance key:"));

    println!(

        "    {}",

        ui::id(format!("oxy identity delegate add {} --scope changes", data.join("keys").join("instance.identity").display()))

    );

    println!(

        "  {} {} {}",

        ui::note(),

        ui::dim("then add agents with"),

        ui::id("spectra agent add NAME --kind KIND --project PROJECT --home DIR")

    );

    Ok(0)

}

pub async fn show(ctx: &Ctx, json: bool) -> Result<i32> {

    let ledger = Ledger::open_read_only(&ctx.db()?).await?;

    let p = Principals::load(&ledger).await?;

    let owner = p.owner().context("no owner is recorded")?;

    let instance = p.instance();

    let delegated =

        instance.is_some_and(|i| owner.delegates_to(&i.hash(), spectra_core::principals::DELEGATION_SCOPE, spectra_core::ids::now_ms()));

    if json {

        println!(

            "{}",

            serde_json::json!({

                "owner": { "name": owner.name, "key": owner.hash().to_hex() },

                "instance": instance.map(|i| serde_json::json!({ "name": i.name, "key": i.hash().to_hex(), "delegated": delegated })),

            })

        );

        return Ok(0);

    }

    println!("{}", ui::section("Owner"));

    println!("{}", ui::kv("name", ui::author(format!("{} <{}>", owner.name, owner.email))));

    println!("{}", ui::kv("key", ui::hash(owner.hash().to_hex())));

    println!("{}", ui::kv("delegates", owner.delegates.len()));

    if let Some(i) = instance {

        println!("{}", ui::section("Instance"));

        println!("{}", ui::kv("name", &i.name));

        println!("{}", ui::kv("key", ui::hash(i.hash().to_hex())));

        if delegated {

            println!("{}", ui::kv("status", ui::ok("delegated by the owner: checkpoints are verifiably yours")));

        } else {

            println!("{}", ui::kv("status", ui::warn("not delegated by the owner yet")));

            println!(

                "  {} {}",

                ui::note(),

                ui::id(format!("oxy identity delegate add {} --scope changes", ctx.data.join("keys").join("instance.identity").display()))

            );

        }

    }

    Ok(0)

}

/// Record the owner's current identity when it has moved on (a delegation

/// added or removed): `spectra identity refresh`.

pub async fn refresh(ctx: &Ctx, owner_home_flag: Option<PathBuf>) -> Result<i32> {

    let ledger = ctx.writer().await?;

    let outcome = refresh_owner(&ledger, &owner_home(ctx, owner_home_flag)).await?;

    ledger.checkpoint().await?;

    match outcome {

        Some(id) => println!(

            "{} {}{}{}",

            ui::done("Recorded"),

            ui::subject("the owner's current identity"),

            ui::sep(),

            ui::hash(id.hash().short(12))

        ),

        None => println!("{} {}", ui::done("Current"), ui::subject("the owner's identity has not moved")),

    }

    Ok(0)

}

/// If the owner's home names a successor of the recorded owner, record it,

/// signed with it, with the identities between. Returns the new identity.

pub async fn refresh_owner(ledger: &Ledger, home: &Path) -> Result<Option<Identity>> {

    let p = Principals::load(ledger).await?;

    let recorded = p.owner().context("no owner is recorded (spectra init)")?.clone();

    let pair = KeyPair::load_home(home)?;

    if pair.key == recorded.hash() {

        return Ok(None);

    }

    let mut chain = Vec::new();

    let mut at = pair.identity.clone();

    while let Some(prev) = at.previous {

        if prev == recorded.hash() {

            break;

        }

        let file = home.join("keys").join(format!("{}.identity", prev.to_hex()));

        at = Identity::decode(

            &std::fs::read(&file).with_context(|| format!("{} is not a successor of the recorded owner", pair.identity.name))?,

        )

        .map_err(|e| anyhow::anyhow!("{}: {e}", file.display()))?;

        chain.push(hex::encode(at.encode()));

        if chain.len() > 1000 {

            bail!("the owner's identity chain is too long to follow");

        }

    }

    if at.previous != Some(recorded.hash()) && pair.identity.previous != Some(recorded.hash()) {

        bail!("{} in {} is not a successor of the recorded owner {}", pair.identity.name, home.display(), recorded.hash().short(12));

    }

    let mut payload = identity_payload(&pair.identity);

    payload["chain"] = chain.into();

    ledger.append_one(signed_event(&pair, "human", "identity.rotated", payload)).await?;

    Ok(Some(pair.identity))

}

fn hostname() -> String {

    std::fs::read_to_string("/etc/hostname")

        .ok()

        .map(|h| h.trim().to_string())

        .filter(|h| !h.is_empty())

        .unwrap_or_else(|| "spectra".into())

}

fn toml_str(s: &str) -> String {

    serde_json::to_string(s).unwrap_or_default()

}