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

use anyhow::{bail, Context, Result};
use clap::{Parser, Subcommand};
use oxy_core::repo::{ChangeStatus, Repo};
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> },
    /// 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,
    },
    /// Undo the last operation
    Undo,
    /// List operations
    #[command(name = "op")]
    Op {
        #[command(subcommand)]
        cmd: OpCmd,
    },
}

#[derive(Subcommand)]
enum OpCmd {
    Log,
}

fn main() {
    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::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!",
                };
                println!("{tag:2} {}", s.path);
            }
            let mut code = 0;
            if snap.base_snapshot.is_conflicted() {
                println!("\nConflicts in the base state:");
                for c in &snap.base_snapshot.tree.conflicts {
                    println!("  tree: {c:?}");
                }
                for (p, f) in &snap.base_snapshot.files {
                    if f.is_conflicted() {
                        println!("  {p}");
                    }
                }
                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!("\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::Undo => {
            let repo = open()?;
            let op = repo.undo()?;
            println!("Undid the last operation; now at: {}", op.command);
            Ok(0)
        }
        Cmd::Op { cmd: OpCmd::Log } => {
            let repo = open()?;
            for (i, (r, op)) in repo.op_log()?.into_iter().enumerate() {
                println!("{}{} {}  {}", if i == 0 { "@ " } else { "  " }, r.short(12), when(op.hlc.wall_ms), op.command);
            }
            Ok(0)
        }
    }
    .map_err(|e: anyhow::Error| e)
    .or_else(|e| {
        if e.to_string().is_empty() {
            bail!("unknown error")
        } else {
            Err(e)
        }
    })
}