//! `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 },

    /// 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::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)

        }

    })

}