//! `oxy`: command-line interface for Oxygen.

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

use clap::{Parser, Subcommand};

use oxy_core::repo::{ChangeStatus, Repo, SignatureStatus};

use std::path::PathBuf;

#[derive(Parser)]

#[command(name = "oxy", version, about = "Oxygen: breathing fresh air into version control")]

struct Cli {

    #[command(subcommand)]

    cmd: Cmd,

}

#[derive(Subcommand)]

enum Cmd {

    /// Create a repository in PATH (default: current directory)

    Init { path: Option<PathBuf> },

    /// Clone a repository from a local path

    Clone { url: String, dest: Option<PathBuf> },

    /// Manage remotes

    Remote {

        #[command(subcommand)]

        cmd: RemoteCmd,

    },

    /// Fetch every bookmark of a remote into its tracking references

    Fetch { remote: Option<String> },

    /// Fetch, then union the remote bookmark into the local one (no merge change)

    Pull { remote: Option<String> },

    /// Push the current bookmark to a remote

    Push {

        remote: Option<String>,

        /// Allow dropping heads the remote has

        #[arg(long)]

        force: bool,

    },

    /// Show the working copy: changed paths and conflicts

    Status,

    /// Record the working copy as a change on the current bookmark

    Commit {

        #[arg(short, long)]

        message: String,

        /// Extra explicit dependencies (ChangeId prefix, #hash prefix)

        #[arg(long = "depends-on")]

        depends_on: Vec<String>,

    },

    /// List changes reachable from the bookmark and the working copy

    Log,

    /// Show what the working copy changes against its base

    Diff,

    /// Show one change (ChangeId prefix, #hash prefix, or @)

    Show { change: String },

    /// Move the working copy to the state formed by CHANGE... (default: the bookmark heads)

    Checkout {

        changes: Vec<String>,

        /// Throw away uncommitted working-copy changes

        #[arg(long)]

        discard: bool,

    },

    /// Report which conflicts of the working copy's base are resolved by the current files

    Resolve,

    /// Serve repositories under ROOT over HTTP (spec §16); TLS is terminated in front

    Serve {

        /// Directory with one repository per subdirectory

        #[arg(long, default_value = ".")]

        root: PathBuf,

        #[arg(long, default_value = "127.0.0.1:8890")]

        bind: String,

        /// Bearer token allowed to push (repeatable); none means open

        #[arg(long = "token")]

        tokens: Vec<String>,

    },

    /// Undo the last operation

    Undo,

    /// Manage the signing identity

    Identity {

        #[command(subcommand)]

        cmd: IdentityCmd,

    },

    /// Verify the signatures on a change (default: every change in the log)

    Verify { change: Option<String> },

    /// Set a repository configuration key (author.*, core.sign, workspace.bookmark, remote.<name>.url|token)

    Config { key: String, value: String },

    /// List operations

    #[command(name = "op")]

    Op {

        #[command(subcommand)]

        cmd: OpCmd,

    },

}

#[derive(Subcommand)]

enum OpCmd {

    Log,

}

#[derive(Subcommand)]

enum RemoteCmd {

    Add { name: String, url: String },

    Remove { name: String },

    List,

}

#[derive(Subcommand)]

enum IdentityCmd {

    /// Generate a composite Ed25519 + ML-DSA-65 key pair and make it the author

    Create {

        #[arg(long)]

        name: Option<String>,

        #[arg(long)]

        email: Option<String>,

    },

    /// Show the configured identity

    Show,

}

fn signature_line(repo: &Repo, h: &oxy_core::hash::ChangeHash) -> Result<String> {

    Ok(match repo.authenticate_change(h)? {

        SignatureStatus::Unsigned => "unsigned".to_string(),

        SignatureStatus::Valid { key, name, email, sealed } => {

            format!("{} by {name} <{email}> key {}", if sealed { "sealed" } else { "signed" }, key.short(12))

        }

        SignatureStatus::Invalid(why) => format!("INVALID signature: {why}"),

    })

}

fn main() {

    // Behave like other CLI tools when output is piped into `head`: die

    // quietly on SIGPIPE instead of panicking on a failed write.

    #[cfg(unix)]

    unsafe {

        libc::signal(libc::SIGPIPE, libc::SIG_DFL);

    }

    match run() {

        Ok(code) => std::process::exit(code),

        Err(e) => {

            eprintln!("error: {e:#}");

            std::process::exit(1);

        }

    }

}

fn open() -> Result<Repo> {

    Repo::open(&std::env::current_dir()?).context("opening repository")

}

fn short_id(c: &oxy_core::objects::Change) -> String {

    c.change_id.short(8)

}

fn when(ms: u64) -> String {

    let secs = (ms / 1000) as i64;

    let days = secs.div_euclid(86_400);

    let rem = secs.rem_euclid(86_400);

    // Civil-from-days (Howard Hinnant), UTC.

    let z = days + 719_468;

    let era = z.div_euclid(146_097);

    let doe = z - era * 146_097;

    let yoe = (doe - doe / 1460 + doe / 36_524 - doe / 146_096) / 365;

    let y = yoe + era * 400;

    let doy = doe - (365 * yoe + yoe / 4 - yoe / 100);

    let mp = (5 * doy + 2) / 153;

    let d = doy - (153 * mp + 2) / 5 + 1;

    let m = if mp < 10 { mp + 3 } else { mp - 9 };

    let y = if m <= 2 { y + 1 } else { y };

    format!("{y:04}-{m:02}-{d:02} {:02}:{:02}:{:02}Z", rem / 3600, (rem % 3600) / 60, rem % 60)

}

fn run() -> Result<i32> {

    let cli = Cli::parse();

    match cli.cmd {

        Cmd::Init { path } => {

            let path = path.unwrap_or(std::env::current_dir()?);

            let repo = Repo::init(&path)?;

            println!("Initialized oxy repository in {}", repo.root().display());

            println!("Bookmark: {}   Author: {} <{}>", repo.config.bookmark, repo.config.author_name, repo.config.author_email);

            Ok(0)

        }

        Cmd::Clone { url, dest } => {

            let dest = dest.unwrap_or_else(|| {

                let base = url.trim_end_matches('/').rsplit('/').next().unwrap_or("repo");

                PathBuf::from(base)

            });

            let repo = Repo::clone(&url, &dest)?;

            let heads = repo.bookmark_heads()?;

            println!("Cloned into {} ({} on {}: {} head{})", repo.root().display(), url, repo.config.bookmark, heads.len(), if heads.len() == 1 { "" } else { "s" });

            Ok(0)

        }

        Cmd::Remote { cmd } => {

            let mut repo = open()?;

            match cmd {

                RemoteCmd::Add { name, url } => {

                    repo.config.set(&format!("remote.{name}.url"), &url)?;

                    repo.save_config()?;

                    println!("Added remote {name} = {url}");

                }

                RemoteCmd::Remove { name } => {

                    repo.config.set(&format!("remote.{name}.url"), "")?;

                    repo.save_config()?;

                    println!("Removed remote {name}");

                }

                RemoteCmd::List => {

                    let view = repo.view()?;

                    for (name, url) in &repo.config.remotes {

                        println!("{name}\t{url}");

                        if let Some(bms) = view.remotes.get(name) {

                            for (bm, st) in bms {

                                let heads = repo.store().get_state(st).map(|s| s.heads.len()).unwrap_or(0);

                                println!("    {bm}: {heads} head{}", if heads == 1 { "" } else { "s" });

                            }

                        }

                    }

                }

            }

            Ok(0)

        }

        Cmd::Fetch { remote } => {

            let repo = open()?;

            let remote = remote.unwrap_or_else(|| "origin".into());

            for (name, heads, n) in repo.fetch(&remote)? {

                println!("{remote}/{name}: {} head{}, {n} new change{}", heads.len(), if heads.len() == 1 { "" } else { "s" }, if n == 1 { "" } else { "s" });

            }

            Ok(0)

        }

        Cmd::Pull { remote } => {

            let repo = open()?;

            let remote = remote.unwrap_or_else(|| "origin".into());

            let r = repo.pull(&remote)?;

            if !r.changed {

                println!("Already up to date.");

            } else {

                println!("{} now has {} head{}{}", repo.config.bookmark, r.heads.len(), if r.heads.len() == 1 { "" } else { "s" }, if r.checked_out { "; working copy updated" } else { "; run `oxy checkout` to update the working copy" });

                let snap = repo.snapshot("oxy pull")?;

                if snap.base_snapshot.is_conflicted() {

                    println!("The result has conflicts; see oxy status.");

                }

            }

            Ok(0)

        }

        Cmd::Push { remote, force } => {

            let repo = open()?;

            let remote = remote.unwrap_or_else(|| "origin".into());

            let mut code = 0;

            for r in repo.push(&remote, force)? {

                if r.ok {

                    println!("{remote}/{}: updated", r.name);

                } else {

                    println!("{remote}/{}: rejected: {}", r.name, r.reason);

                    code = 1;

                }

            }

            Ok(code)

        }

        Cmd::Status => {

            let repo = open()?;

            let snap = repo.snapshot("oxy status")?;

            let heads = repo.bookmark_heads()?;

            println!(

                "Working copy: {} on {} ({} head{})",

                snap.wc.change_id.short(8),

                repo.config.bookmark,

                heads.len(),

                if heads.len() == 1 { "" } else { "s" }

            );

            if snap.statuses.is_empty() {

                println!("The working copy is clean.");

            }

            for s in &snap.statuses {

                let tag = match s.status {

                    ChangeStatus::Added => "A",

                    ChangeStatus::Modified => "M",

                    ChangeStatus::Removed => "D",

                    ChangeStatus::ModeChanged => "X",

                    ChangeStatus::ConflictEdited => "C!",

                    ChangeStatus::Resolved => "R",

                };

                println!("{tag:2} {}", s.path);

            }

            let mut code = 0;

            if snap.base_snapshot.is_conflicted() {

                println!("\nConflicts in the base state (edit the marked files, or the .oxy-conflict-N candidates, then commit):");

                for c in &snap.base_snapshot.tree.conflicts {

                    println!("  tree: {c:?}");

                }

                for (p, f) in &snap.base_snapshot.files {

                    if f.is_conflicted() {

                        let state = match snap.statuses.iter().find(|s| s.path == *p).map(|s| s.status) {

                            Some(ChangeStatus::Resolved) => "resolved in working copy",

                            Some(ChangeStatus::ConflictEdited) => "markers remain",

                            _ => "unresolved",

                        };

                        println!("  {p}  ({state})");

                    }

                }

                code = 2;

            }

            Ok(code)

        }

        Cmd::Commit { message, depends_on } => {

            let repo = open()?;

            let mut deps = Vec::new();

            for d in &depends_on {

                deps.push(repo.resolve_change(d)?);

            }

            let h = repo.commit(&message, &deps)?;

            let c = repo.store().get_change(&h)?;

            println!("Committed {} #{}: {}", short_id(&c), h.short(12), message.lines().next().unwrap_or(""));

            Ok(0)

        }

        Cmd::Log => {

            let repo = open()?;

            repo.snapshot("oxy log")?;

            for e in repo.log()? {

                let c = &e.change;

                let mut flags = Vec::new();

                if e.is_working_copy {

                    flags.push("working copy");

                }

                if e.is_head {

                    flags.push("head");

                }

                let flags = if flags.is_empty() { String::new() } else { format!(" ({})", flags.join(", ")) };

                println!("{} #{}{}", short_id(c), e.hash.short(12), flags);

                println!("    {}", when(c.hlc.wall_ms));

                if !c.deps.is_empty() {

                    println!("    deps: {}", c.deps.iter().map(|d| format!("#{}", d.short(12))).collect::<Vec<_>>().join(" "));

                }

                let msg = if c.message.is_empty() { "(no description)" } else { &c.message };

                for line in msg.lines() {

                    println!("    {line}");

                }

                println!();

            }

            Ok(0)

        }

        Cmd::Diff => {

            let repo = open()?;

            let snap = repo.snapshot("oxy diff")?;

            print!("{}", oxy_core::repo::render_change(&snap.wc, &snap.base, &snap.base_snapshot));

            Ok(0)

        }

        Cmd::Show { change } => {

            let repo = open()?;

            repo.snapshot("oxy show")?;

            let h = repo.resolve_change(&change)?;

            let c = repo.store().get_change(&h)?;

            println!("change {} #{}", short_id(&c), h);

            println!("kind:   {:?}", c.kind);

            println!("date:   {}", when(c.hlc.wall_ms));

            println!("deps:   {}", c.deps.iter().map(|d| format!("#{}", d.short(12))).collect::<Vec<_>>().join(" "));

            println!("sig:    {}", signature_line(&repo, &h)?);

            println!("\n{}\n", if c.message.is_empty() { "(no description)" } else { &c.message });

            print!("{}", repo.describe_change(&h)?);

            Ok(0)

        }

        Cmd::Checkout { changes, discard } => {

            let repo = open()?;

            let heads = if changes.is_empty() {

                repo.bookmark_heads()?

            } else {

                changes.iter().map(|c| repo.resolve_change(c)).collect::<Result<Vec<_>, _>>()?

            };

            let spec = if changes.is_empty() { repo.config.bookmark.clone() } else { changes.join(" ") };

            let r = repo.checkout(&heads, discard, &format!("oxy checkout {spec}"))?;

            println!("Working copy now on {spec}: {} file(s) written, {} removed", r.written, r.removed);

            if r.conflicted {

                println!("This state has conflicts; see oxy status.");

            }

            Ok(0)

        }

        Cmd::Resolve => {

            let repo = open()?;

            let snap = repo.snapshot("oxy resolve")?;

            if !snap.base_snapshot.is_conflicted() {

                println!("The working copy's base has no conflicts.");

                return Ok(0);

            }

            let mut remaining = 0;

            for (p, f) in &snap.base_snapshot.files {

                if !f.is_conflicted() {

                    continue;

                }

                match snap.statuses.iter().find(|s| s.path == *p).map(|s| s.status) {

                    Some(ChangeStatus::Resolved) => println!("resolved   {p}"),

                    Some(ChangeStatus::ConflictEdited) => {

                        remaining += 1;

                        println!("markers    {p}");

                    }

                    _ => {

                        remaining += 1;

                        println!("unresolved {p}");

                    }

                }

            }

            for c in &snap.base_snapshot.tree.conflicts {

                remaining += 1;

                println!("tree       {c:?}");

            }

            if remaining == 0 {

                println!("All conflicts are resolved; `oxy commit` will record the resolution.");

                Ok(0)

            } else {

                Ok(2)

            }

        }

        Cmd::Serve { root, bind, tokens } => {

            let listener = std::net::TcpListener::bind(&bind).with_context(|| format!("binding {bind}"))?;

            let root = root.canonicalize()?;

            println!("Serving repositories under {} on http://{bind}/<repo>/oxy/v1/ ({})", root.display(), if tokens.is_empty() { "open: no push tokens configured" } else { "push requires a token" });

            oxy_server::run_blocking(listener, oxy_server::ServerConfig { root, tokens })?;

            Ok(0)

        }

        Cmd::Undo => {

            let repo = open()?;

            let op = repo.undo()?;

            println!("Undid the last operation; now at: {}", op.command);

            Ok(0)

        }

        Cmd::Identity { cmd: IdentityCmd::Create { name, email } } => {

            let mut repo = open()?;

            let name = name.unwrap_or_else(|| repo.config.author_name.clone());

            let email = email.unwrap_or_else(|| repo.config.author_email.clone());

            let (key, _) = repo.create_identity(&name, &email)?;

            println!("Created identity {name} <{email}>");

            println!("KeyId: {key}");

            println!("Secret key stored under {}", oxy_core::repo::default_keys_dir().display());

            if !repo.config.sign_changes {

                println!("Changes will carry this author; run `oxy config core.sign change` to sign each commit.");

            }

            Ok(0)

        }

        Cmd::Identity { cmd: IdentityCmd::Show } => {

            let repo = open()?;

            match repo.config.author_key {

                None => println!("No identity configured; run `oxy identity create`."),

                Some(key) => {

                    let id = repo.identity(&key)?;