//! The owner's admin commands over admin.sock: approvals, approve, refuse, grants check.

use std::io::{self, Write};
use std::os::unix::net::UnixStream;
use std::path::{Path, PathBuf};

use proto::{
    Approve, DecisionRecord, DenyReason, Empty, Envelope, ErrorCode, FrameError, Message,
    PROTOCOL_VERSION, PendingApproval, Refuse, Timestamp, WireError, read_frame, write_frame,
};

use crate::chat::code_name;
use crate::escape::escape_json_text;

// Ask brokerd for one message and read one answer.
pub fn request(socket: &Path, msg: Message) -> Result<Message, AdminError> {
    let mut stream =
        UnixStream::connect(socket).map_err(|e| AdminError::Connect(socket.to_path_buf(), e))?;
    let env = Envelope {
        v: PROTOCOL_VERSION,
        id: 1,
        r#final: true,
        msg,
    };
    write_frame(&mut stream, &env).map_err(AdminError::Frame)?;
    let answer = read_frame(&mut stream).map_err(AdminError::Frame)?;
    if answer.id != 1 || !answer.r#final {
        return Err(AdminError::Protocol(
            "expected an answer for request 1".to_string(),
        ));
    }
    match answer.msg {
        Message::Error(w) => Err(AdminError::Refused(w)),
        other => Ok(other),
    }
}

// Ask brokerd for the list of approvals waiting, or report an answer of the wrong kind.
pub fn list(socket: &Path) -> Result<Vec<PendingApproval>, AdminError> {
    match request(socket, Message::Approvals(Empty {}))? {
        Message::ApprovalList(list) => Ok(list.items),
        _ => Err(AdminError::Protocol(
            "expected an approval list".to_string(),
        )),
    }
}

#[derive(Debug)]
pub enum AdminError {
    Connect(PathBuf, std::io::Error),
    Frame(FrameError),
    Refused(WireError),
    Protocol(String),
}

impl std::fmt::Display for AdminError {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            AdminError::Connect(p, e) => write!(f, "cannot reach brokerd at {}: {e}", p.display()),
            AdminError::Frame(e) => write!(f, "{e}"),
            AdminError::Refused(w) => write!(f, "{}: {}", code_name(w.code), w.detail),
            AdminError::Protocol(s) => write!(f, "{s}"),
        }
    }
}

// An error writing the output is reported like any other failure, with the message preserved.
impl From<std::io::Error> for AdminError {
    fn from(e: std::io::Error) -> Self {
        AdminError::Protocol(e.to_string())
    }
}

impl std::error::Error for AdminError {}

pub fn cmd_approvals(
    socket: &Path,
    now: Timestamp,
    out: &mut dyn Write,
) -> Result<bool, AdminError> {
    let items = list(socket)?;
    if items.is_empty() {
        writeln!(out, "no pending approvals")?;
    } else {
        for item in &items {
            write_block(out, item, now)?;
        }
    }
    Ok(true)
}

pub fn cmd_approve(socket: &Path, approval: u64, out: &mut dyn Write) -> Result<bool, AdminError> {
    let msg = match request(socket, Message::Approve(Approve { approval })) {
        Ok(m) => m,
        Err(AdminError::Refused(w)) if w.code == ErrorCode::NoSuchApproval => {
            writeln!(
                out,
                "{approval}: no such approval (already answered or expired)"
            )?;
            return Ok(false);
        }
        Err(e) => return Err(e),
    };
    match msg {
        Message::ApproveResult(result) => match result.outcome {
            DecisionRecord::Allowed {} | DecisionRecord::Ask {} => {
                writeln!(out, "approved {approval}: runs")?;
                Ok(true)
            }
            DecisionRecord::Denied { reason } => {
                writeln!(out, "approved {approval}: denied ({})", reason_name(reason))?;
                Ok(false)
            }
        },
        _ => Err(AdminError::Protocol("unexpected answer".to_string())),
    }
}

pub fn cmd_refuse(
    socket: &Path,
    approval: u64,
    reason: Option<&str>,
    out: &mut dyn Write,
) -> Result<bool, AdminError> {
    let msg = match request(
        socket,
        Message::Refuse(Refuse {
            approval,
            reason: reason.map(str::to_string),
        }),
    ) {
        Ok(m) => m,
        Err(AdminError::Refused(w)) if w.code == ErrorCode::NoSuchApproval => {
            writeln!(
                out,
                "{approval}: no such approval (already answered or expired)"
            )?;
            return Ok(false);
        }
        Err(e) => return Err(e),
    };
    match msg {
        Message::Ok(_) => {
            writeln!(out, "refused {approval}")?;
            Ok(true)
        }
        _ => Err(AdminError::Protocol("unexpected answer".to_string())),
    }
}

pub fn cmd_grants_check(socket: &Path, out: &mut dyn Write) -> Result<bool, AdminError> {
    let msg = request(socket, Message::CheckGrants(Empty {}))?;
    match msg {
        Message::GrantsReport(report) => {
            if report.problems.is_empty() {
                writeln!(out, "grants: ok")?;
                Ok(true)
            } else {
                for problem in &report.problems {
                    writeln!(
                        out,
                        "{}{}: {}",
                        escape_json_text(&problem.file),
                        match problem.line {
                            Some(line) => format!(":{line}"),
                            None => String::new(),
                        },
                        escape_json_text(&problem.problem)
                    )?;
                }
                Ok(false)
            }
        }
        _ => Err(AdminError::Protocol("unexpected answer".to_string())),
    }
}

pub fn reason_name(reason: DenyReason) -> &'static str {
    match reason {
        DenyReason::NoGrant => "no_grant",
        DenyReason::GrantExpired => "grant_expired",
        DenyReason::TaintTooHigh => "taint_too_high",
        DenyReason::DeniedByGrant => "denied_by_grant",
        DenyReason::ApprovalRefused => "approval_refused",
        DenyReason::ApprovalExpired => "approval_expired",
        DenyReason::GrantsInvalid => "grants_invalid",
        DenyReason::AuditUnavailable => "audit_unavailable",
        DenyReason::InvalidArguments => "invalid_arguments",
        DenyReason::StateUnreadable => "state_unreadable",
    }
}

// The approvals table is one block per item: a summary line, then the tool and arguments.
pub fn write_block(out: &mut dyn Write, item: &PendingApproval, now: Timestamp) -> io::Result<()> {
    let age = now.unix_millis().saturating_sub(item.created.unix_millis());
    let until = item.expires.unix_millis().saturating_sub(now.unix_millis());
    writeln!(
        out,
        "{}  {} ago  {}  session {}  grant {}  taint {}",
        item.approval,
        span(age),
        expiry(until, now >= item.expires),
        session_shown(item.session.as_str()),
        escape_json_text(&item.grant),
        taint_name(item.taint),
    )?;
    writeln!(
        out,
        "    {} {}",
        escape_json_text(&item.tool),
        escape_json_text(&item.arguments)
    )?;
    Ok(())
}

// A span of whole seconds, minutes, or hours, rounded down.
fn span(ms: u64) -> String {
    let secs = ms / 1000;
    let mins = secs / 60;
    let hours = mins / 60;
    if mins == 0 {
        format!("{secs} s")
    } else if hours == 0 {
        format!("{mins} min")
    } else {
        format!("{hours} h")
    }
}

// Whether the approval has expired, or how long until it does.
fn expiry(until: u64, expired: bool) -> String {
    if expired {
        "expired".to_string()
    } else {
        format!("expires in {}", span(until))
    }
}

// A session id longer than ten characters is cut to nine and an ellipsis.
fn session_shown(session: &str) -> String {
    if session.chars().count() > 10 {
        let head: String = session.chars().take(9).collect();
        format!("{head}…")
    } else {
        session.to_string()
    }
}

// The taint of a decision is its wire name.
fn taint_name(taint: proto::DataClass) -> &'static str {
    match taint {
        proto::DataClass::Public => "public",
        proto::DataClass::Private => "private",
        proto::DataClass::Secret => "secret",
    }
}