qryxip/investigate-dropbox.rs

## investigate-dropbox.rs
//! ```cargo
//! [package]
//! name = "invesigate-dropbox"
//! version = "0.0.0"
//! authors = ["Ryo Yamashita <qryxip@gmail.com>"]
//! edition = "2018"
//! publish = false
//!
//! [dependencies]
//! anyhow = "1.0.32"
//! atty = "0.2.14"
//! maplit = "1.0.2"
//! reqwest = { version = "0.10.7", features = ["blocking", "json"] }
//! serde = { version = "1.0.115", features = ["derive"] }
//! serde_json = "1.0.57"
//! structopt = "0.3.16"
//! termcolor = "1.1.0"
//! ```

use anyhow::{anyhow, bail, Context as _};
use maplit::btreeset;
use reqwest::Method;
use serde::Deserialize;
use serde_json::json;
use std::{
    collections::BTreeSet,
    convert, env, fmt,
    io::{self, Write as _},
    time::Duration,
};
use structopt::StructOpt;
use termcolor::{BufferedStandardStream, Color, ColorChoice, ColorSpec, WriteColor as _};

#[derive(StructOpt)]
struct Opt {}

fn main() -> anyhow::Result<()> {
    Opt::from_args();

    let mut shell = Shell::new();
    let client = client()?;
    let access_token = access_token()?;

    let dir_names = list_folder(&mut shell, &client, &access_token, "")?;

    let mut different = btreeset!();
    let mut arc_abcd = btreeset!();
    let mut arc_cdef = btreeset!();
    let mut arc_abcdef = btreeset!();

    for dir_name in dir_names {
        let contest_ids = match &*dir_name {
            "ARC060" => vec!["arc060".to_owned(), "abc044".to_owned()],
            "ARC061" => vec!["arc061".to_owned(), "abc045".to_owned()],
            "ARC062" => vec!["arc062".to_owned(), "abc046".to_owned()],
            "ARC063" => vec!["arc063".to_owned(), "abc047".to_owned()],
            "ARC064" => vec!["arc064".to_owned(), "abc048".to_owned()],
            "ARC065" => vec!["arc065".to_owned(), "abc049".to_owned()],
            "ARC066" => vec!["arc066".to_owned(), "abc050".to_owned()],
            "ARC067" => vec!["arc067".to_owned(), "abc052".to_owned()],
            "ARC068" => vec!["arc068".to_owned(), "abc053".to_owned()],
            "ARC069" => vec!["arc069".to_owned(), "abc055".to_owned()],
            "ARC070" => vec!["arc070".to_owned(), "abc056".to_owned()],
            "ARC071" => vec!["arc071".to_owned(), "abc058".to_owned()],
            "ARC072" => vec!["arc072".to_owned(), "abc059".to_owned()],
            "ARC073" => vec!["arc073".to_owned(), "abc060".to_owned()],
            "ARC074" => vec!["arc074".to_owned(), "abc062".to_owned()],
            "ARC075" => vec!["arc075".to_owned(), "abc063".to_owned()],
            "ARC076" => vec!["arc076".to_owned(), "abc065".to_owned()],
            "ARC077" => vec!["arc077".to_owned(), "abc066".to_owned()],
            "ARC078" => vec!["arc078".to_owned(), "abc067".to_owned()],
            "ARC079" => vec!["arc079".to_owned(), "abc068".to_owned()],
            "ARC080" => vec!["arc080".to_owned(), "abc069".to_owned()],
            "ARC081" => vec!["arc081".to_owned(), "abc071".to_owned()],
            "ARC082" => vec!["arc082".to_owned(), "abc072".to_owned()],
            "ARC083" => vec!["arc083".to_owned(), "abc074".to_owned()],
            "ARC084" => vec!["arc084".to_owned(), "abc077".to_owned()],
            "ARC085" => vec!["arc085".to_owned(), "abc078".to_owned()],
            "ARC086" => vec!["arc086".to_owned(), "abc081".to_owned()],
            "ARC087" => vec!["arc087".to_owned(), "abc082".to_owned()],
            "ARC088" => vec!["arc088".to_owned(), "abc083".to_owned()],
            "ARC089" => vec!["arc089".to_owned(), "abc086".to_owned()],
            "ARC090" => vec!["arc090".to_owned(), "abc087".to_owned()],
            "ARC091" => vec!["arc091".to_owned(), "abc090".to_owned()],
            "ARC092" => vec!["arc092".to_owned(), "abc091".to_owned()],
            "ARC093" => vec!["arc093".to_owned(), "abc092".to_owned()],
            "ARC094" => vec!["arc094".to_owned(), "abc093".to_owned()],
            "ARC095" => vec!["arc095".to_owned(), "abc094".to_owned()],
            "ARC096" => vec!["arc096".to_owned(), "abc095".to_owned()],
            "ARC097" => vec!["arc097".to_owned(), "abc097".to_owned()],
            "ARC098" => vec!["arc098".to_owned(), "abc098".to_owned()],
            "ARC099" => vec!["arc099".to_owned(), "abc101".to_owned()],
            "ARC100" => vec!["arc100".to_owned(), "abc102".to_owned()],
            "ARC101" => vec!["arc101".to_owned(), "abc107".to_owned()],
            "ARC102" => vec!["arc102".to_owned(), "abc108".to_owned()],
            "ARC103" => vec!["arc103".to_owned(), "abc111".to_owned()],
            "ARC058_ABC042" => vec!["arc058".to_owned(), "abc042".to_owned()],
            "ARC059_ABC043" => vec!["arc059".to_owned(), "abc043".to_owned()],
            "2019ddccqual" => vec!["ddcc2019-qual".to_owned()],
            "2019exa" => vec!["exawizards2019".to_owned()],
            "2019nikkei_qual" => vec!["nikkei2019-qual".to_owned()],
            "2019yahoo_qual" => vec!["yahoo-procon2019-qual".to_owned()],
            "2020_dwango_qual" => vec!["dwacon6th-prelims".to_owned()],
            "2020_hitachi" => vec!["hitachi2020".to_owned()],
            "2020_panasonic" => vec!["panasonic2020".to_owned()],
            "CodeFestival2016EliminationTournament" => vec![
                "cf16-tournament-round1-open".to_owned(),
                "cf16-tournament-round2-open".to_owned(),
                "cf16-tournament-round3-open".to_owned(),
            ],
            "CodeFestival2016Exhibition" => vec!["cf16-exhibition-open".to_owned()],
            "CodeFestival2016Final" => vec!["cf16-final-open".to_owned()],
            "CodeFestival2016GrandFinal" => vec!["cf16-exhibition-final-open".to_owned()],
            "CodeFestival2016QualA" => vec!["code-festival-2016-quala".to_owned()],
            "CodeFestival2016QualB" => vec!["code-festival-2016-qualb".to_owned()],
            "CodeFestival2016QualC" => vec!["code-festival-2016-qualc".to_owned()],
            "CodeFestival2016Relay" => vec!["cf16-relay-open".to_owned()],
            "CodeFestival2017Exhibition" => vec!["cf17-exhibition-open".to_owned()],
            "CodeFestival2017Final" => vec!["cf17-final-open".to_owned()],
            "CodeFestival2017QualA" => vec!["code-festival-2017-quala".to_owned()],
            "CodeFestival2017QualB" => vec!["code-festival-2017-qualb".to_owned()],
            "CodeFestival2017QualC" => vec!["code-festival-2017-qualc".to_owned()],
            "CodeFestival2017Relay" => vec!["cf17-relay-open".to_owned()],
            "CodeFestival2017Tournament" => vec![
                "cf17-tournament-round1-open".to_owned(),
                "cf17-tournament-round2-open".to_owned(),
                "cf17-tournament-round3-open".to_owned(),
            ],
            "MUJIN2017" => vec!["mujin-pc-2017".to_owned()],
            "diverta2_2019" => vec!["diverta2019-2".to_owned()],
            "diverta_2019" => vec!["diverta2019".to_owned()],
            "jsc2019" => vec!["jsc2019-qual".to_owned()],
            "msolutions2019" => vec!["m-solutions2019".to_owned()],
            "nikkeiqual_2019" => vec!["nikkei2019-qual".to_owned()],
            "tenka1_2017" => vec!["tenka1-2017".to_owned()],
            "tenka1_2018" => vec!["tenka1-2018".to_owned()],
            "tenka1_2019" => vec!["tenka1-2019".to_owned()],
            dir_name => vec![dir_name.to_ascii_lowercase()],
        };

        for contest_id in contest_ids {
            if !exists(&mut shell, &client, &contest_id)? {
                different.insert((dir_name.clone(), contest_id.clone()));
            }
        }

        if dir_name.starts_with("ARC") && dir_name.len() == 6 {
            let problems = list_folder(
                &mut shell,
                &client,
                &access_token,
                &format!("/{}", dir_name),
            )?;

            if problems.iter().eq(&["A", "B", "C", "D"]) {
                arc_abcd.insert(dir_name);
            } else if problems.iter().eq(&["C", "D", "E", "F"]) {
                arc_cdef.insert(dir_name);
            } else if problems.iter().eq(&["A", "B", "C", "D", "E", "F"]) {
                arc_abcdef.insert(dir_name);
            } else {
                bail!("?????: {:?}", problems);
            }
        }
    }

    if different.is_empty() {
        shell.info("found all")?;
    }

    for (dir_name, contest_id) in different {
        shell.info(format!("not found: {:?} -> {:?}", dir_name, contest_id))?;
    }

    if !arc_abcd.is_empty() {
        for name in arc_abcd {
            shell.info(format!("ARC - A, B, C, D: {:?}", name))?;
        }
    }
    if !arc_cdef.is_empty() {
        for name in arc_cdef {
            shell.info(format!("ARC - C, D, E, F: {:?}", name))?;
        }
    }
    if !arc_abcdef.is_empty() {
        for name in arc_abcdef {
            shell.info(format!("ARC - A, B, C, D, E, F: {:?}", name))?;
        }
    }

    Ok(())
}

fn client() -> reqwest::Result<reqwest::blocking::Client> {
    const USER_AGENT: &str = "qryxip@gmail.com";
    const TIMEOUT: Option<Duration> = Some(Duration::from_secs(30));

    reqwest::blocking::ClientBuilder::new()
        .user_agent(USER_AGENT)
        .timeout(TIMEOUT)
        .build()
}

fn access_token() -> anyhow::Result<String> {
    env::var("DROPBOX_ACCESS_TOKEN").with_context(|| "could not read `$DROPBOX_ACCESS_TOKEN`")
}

fn list_folder(
    shell: &mut Shell,
    client: &reqwest::blocking::Client,
    access_token: &str,
    path: &str,
) -> anyhow::Result<BTreeSet<String>> {
    static SHARED_LINK_URL: &str =
        "https://www.dropbox.com/sh/arnpe0ef5wds8cv/AAAk_SECQ2Nc6SVGii3rHX6Fa?dl=0";

    #[derive(Deserialize)]
    #[serde(untagged)]
    enum ListFolderOutcome {
        Ok(ListFolder),
        Err(serde_json::Value),
    }

    #[derive(Deserialize)]
    struct ListFolder {
        entries: Vec<ListFolderEntry>,
    }

    #[derive(Deserialize)]
    struct ListFolderEntry {
        name: String,
    }

    let res = request_with_message(
        shell,
        client,
        Method::POST,
        "https://api.dropboxapi.com/2/files/list_folder",
        |req| {
            req.bearer_auth(access_token)
                .json(&json!({ "shared_link": { "url": SHARED_LINK_URL }, "path": path }))
        },
    )?;

    if res.status() == 200 {
        let ListFolder { entries } = res.json()?;
        Ok(entries
            .into_iter()
            .map(|ListFolderEntry { name }| name)
            .collect())
    } else {
        let msg = res.text()?;
        let msg = serde_json::to_string_pretty(&msg).unwrap_or(msg);
        Err(anyhow!("{}", msg).context("API error"))
    }
}

fn exists(
    shell: &mut Shell,
    client: &reqwest::blocking::Client,
    contest_id: &str,
) -> anyhow::Result<bool> {
    let status = request_with_message(
        shell,
        client,
        Method::GET,
        &format!("https://atcoder.jp/contests/{}", contest_id),
        convert::identity,
    )?
    .status();

    match status.as_u16() {
        200 => Ok(true),
        404 => Ok(false),
        _ => bail!("{}", status),
    }
}

fn request_with_message(
    shell: &mut Shell,
    client: &reqwest::blocking::Client,
    method: Method,
    url: &str,
    modify_req: impl FnOnce(reqwest::blocking::RequestBuilder) -> reqwest::blocking::RequestBuilder,
) -> anyhow::Result<reqwest::blocking::Response> {
    let req = modify_req(client.request(method.clone(), url));
    shell.network(format!("{}: {}", method, url))?;
    let res = req.send()?;
    shell.network(res.status())?;
    Ok(res)
}

struct Shell(BufferedStandardStream);

impl Shell {
    fn new() -> Self {
        Self(BufferedStandardStream::stderr(
            if atty::is(atty::Stream::Stderr) {
                ColorChoice::Auto
            } else {
                ColorChoice::Never
            },
        ))
    }

    fn info(&mut self, message: impl fmt::Display) -> io::Result<()> {
        self.print("info:", message, Color::Cyan)
    }

    fn network(&mut self, message: impl fmt::Display) -> io::Result<()> {
        self.print("network:", message, Color::Magenta)
    }

    fn print(
        &mut self,
        status: impl fmt::Display,
        message: impl fmt::Display,
        color: Color,
    ) -> io::Result<()> {
        self.0
            .set_color(ColorSpec::new().set_bold(true).set_fg(Some(color)))?;
        write!(self.0, "{}", status)?;
        self.0.reset()?;
        writeln!(self.0, " {}", message)?;
        self.0.flush()
    }
}
	//! ```cargo
	//! [package]
	//! name = "invesigate-dropbox"
	//! version = "0.0.0"
	//! authors = ["Ryo Yamashita <qryxip@gmail.com>"]
	//! edition = "2018"
	//! publish = false
	//!
	//! [dependencies]
	//! anyhow = "1.0.32"
	//! atty = "0.2.14"
	//! maplit = "1.0.2"
	//! reqwest = { version = "0.10.7", features = ["blocking", "json"] }
	//! serde = { version = "1.0.115", features = ["derive"] }
	//! serde_json = "1.0.57"
	//! structopt = "0.3.16"
	//! termcolor = "1.1.0"
	//! ```

	use anyhow::{anyhow, bail, Context as _};
	use maplit::btreeset;
	use reqwest::Method;
	use serde::Deserialize;
	use serde_json::json;
	use std::{
	collections::BTreeSet,
	convert, env, fmt,
	io::{self, Write as _},
	time::Duration,
	};
	use structopt::StructOpt;
	use termcolor::{BufferedStandardStream, Color, ColorChoice, ColorSpec, WriteColor as _};

	#[derive(StructOpt)]
	struct Opt {}

	fn main() -> anyhow::Result<()> {
	Opt::from_args();

	let mut shell = Shell::new();
	let client = client()?;
	let access_token = access_token()?;

	let dir_names = list_folder(&mut shell, &client, &access_token, "")?;

	let mut different = btreeset!();
	let mut arc_abcd = btreeset!();
	let mut arc_cdef = btreeset!();
	let mut arc_abcdef = btreeset!();

	for dir_name in dir_names {
	let contest_ids = match &*dir_name {
	"ARC060" => vec!["arc060".to_owned(), "abc044".to_owned()],
	"ARC061" => vec!["arc061".to_owned(), "abc045".to_owned()],
	"ARC062" => vec!["arc062".to_owned(), "abc046".to_owned()],
	"ARC063" => vec!["arc063".to_owned(), "abc047".to_owned()],
	"ARC064" => vec!["arc064".to_owned(), "abc048".to_owned()],
	"ARC065" => vec!["arc065".to_owned(), "abc049".to_owned()],
	"ARC066" => vec!["arc066".to_owned(), "abc050".to_owned()],
	"ARC067" => vec!["arc067".to_owned(), "abc052".to_owned()],
	"ARC068" => vec!["arc068".to_owned(), "abc053".to_owned()],
	"ARC069" => vec!["arc069".to_owned(), "abc055".to_owned()],
	"ARC070" => vec!["arc070".to_owned(), "abc056".to_owned()],
	"ARC071" => vec!["arc071".to_owned(), "abc058".to_owned()],
	"ARC072" => vec!["arc072".to_owned(), "abc059".to_owned()],
	"ARC073" => vec!["arc073".to_owned(), "abc060".to_owned()],
	"ARC074" => vec!["arc074".to_owned(), "abc062".to_owned()],
	"ARC075" => vec!["arc075".to_owned(), "abc063".to_owned()],
	"ARC076" => vec!["arc076".to_owned(), "abc065".to_owned()],
	"ARC077" => vec!["arc077".to_owned(), "abc066".to_owned()],
	"ARC078" => vec!["arc078".to_owned(), "abc067".to_owned()],
	"ARC079" => vec!["arc079".to_owned(), "abc068".to_owned()],
	"ARC080" => vec!["arc080".to_owned(), "abc069".to_owned()],
	"ARC081" => vec!["arc081".to_owned(), "abc071".to_owned()],
	"ARC082" => vec!["arc082".to_owned(), "abc072".to_owned()],
	"ARC083" => vec!["arc083".to_owned(), "abc074".to_owned()],
	"ARC084" => vec!["arc084".to_owned(), "abc077".to_owned()],
	"ARC085" => vec!["arc085".to_owned(), "abc078".to_owned()],
	"ARC086" => vec!["arc086".to_owned(), "abc081".to_owned()],
	"ARC087" => vec!["arc087".to_owned(), "abc082".to_owned()],
	"ARC088" => vec!["arc088".to_owned(), "abc083".to_owned()],
	"ARC089" => vec!["arc089".to_owned(), "abc086".to_owned()],
	"ARC090" => vec!["arc090".to_owned(), "abc087".to_owned()],
	"ARC091" => vec!["arc091".to_owned(), "abc090".to_owned()],
	"ARC092" => vec!["arc092".to_owned(), "abc091".to_owned()],
	"ARC093" => vec!["arc093".to_owned(), "abc092".to_owned()],
	"ARC094" => vec!["arc094".to_owned(), "abc093".to_owned()],
	"ARC095" => vec!["arc095".to_owned(), "abc094".to_owned()],
	"ARC096" => vec!["arc096".to_owned(), "abc095".to_owned()],
	"ARC097" => vec!["arc097".to_owned(), "abc097".to_owned()],
	"ARC098" => vec!["arc098".to_owned(), "abc098".to_owned()],
	"ARC099" => vec!["arc099".to_owned(), "abc101".to_owned()],
	"ARC100" => vec!["arc100".to_owned(), "abc102".to_owned()],
	"ARC101" => vec!["arc101".to_owned(), "abc107".to_owned()],
	"ARC102" => vec!["arc102".to_owned(), "abc108".to_owned()],
	"ARC103" => vec!["arc103".to_owned(), "abc111".to_owned()],
	"ARC058_ABC042" => vec!["arc058".to_owned(), "abc042".to_owned()],
	"ARC059_ABC043" => vec!["arc059".to_owned(), "abc043".to_owned()],
	"2019ddccqual" => vec!["ddcc2019-qual".to_owned()],
	"2019exa" => vec!["exawizards2019".to_owned()],
	"2019nikkei_qual" => vec!["nikkei2019-qual".to_owned()],
	"2019yahoo_qual" => vec!["yahoo-procon2019-qual".to_owned()],
	"2020_dwango_qual" => vec!["dwacon6th-prelims".to_owned()],
	"2020_hitachi" => vec!["hitachi2020".to_owned()],
	"2020_panasonic" => vec!["panasonic2020".to_owned()],
	"CodeFestival2016EliminationTournament" => vec![
	"cf16-tournament-round1-open".to_owned(),
	"cf16-tournament-round2-open".to_owned(),
	"cf16-tournament-round3-open".to_owned(),
	],
	"CodeFestival2016Exhibition" => vec!["cf16-exhibition-open".to_owned()],
	"CodeFestival2016Final" => vec!["cf16-final-open".to_owned()],
	"CodeFestival2016GrandFinal" => vec!["cf16-exhibition-final-open".to_owned()],
	"CodeFestival2016QualA" => vec!["code-festival-2016-quala".to_owned()],
	"CodeFestival2016QualB" => vec!["code-festival-2016-qualb".to_owned()],
	"CodeFestival2016QualC" => vec!["code-festival-2016-qualc".to_owned()],
	"CodeFestival2016Relay" => vec!["cf16-relay-open".to_owned()],
	"CodeFestival2017Exhibition" => vec!["cf17-exhibition-open".to_owned()],
	"CodeFestival2017Final" => vec!["cf17-final-open".to_owned()],
	"CodeFestival2017QualA" => vec!["code-festival-2017-quala".to_owned()],
	"CodeFestival2017QualB" => vec!["code-festival-2017-qualb".to_owned()],
	"CodeFestival2017QualC" => vec!["code-festival-2017-qualc".to_owned()],
	"CodeFestival2017Relay" => vec!["cf17-relay-open".to_owned()],
	"CodeFestival2017Tournament" => vec![
	"cf17-tournament-round1-open".to_owned(),
	"cf17-tournament-round2-open".to_owned(),
	"cf17-tournament-round3-open".to_owned(),
	],
	"MUJIN2017" => vec!["mujin-pc-2017".to_owned()],
	"diverta2_2019" => vec!["diverta2019-2".to_owned()],
	"diverta_2019" => vec!["diverta2019".to_owned()],
	"jsc2019" => vec!["jsc2019-qual".to_owned()],
	"msolutions2019" => vec!["m-solutions2019".to_owned()],
	"nikkeiqual_2019" => vec!["nikkei2019-qual".to_owned()],
	"tenka1_2017" => vec!["tenka1-2017".to_owned()],
	"tenka1_2018" => vec!["tenka1-2018".to_owned()],
	"tenka1_2019" => vec!["tenka1-2019".to_owned()],
	dir_name => vec![dir_name.to_ascii_lowercase()],
	};

	for contest_id in contest_ids {
	if !exists(&mut shell, &client, &contest_id)? {
	different.insert((dir_name.clone(), contest_id.clone()));
	}
	}

	if dir_name.starts_with("ARC") && dir_name.len() == 6 {
	let problems = list_folder(
	&mut shell,
	&client,
	&access_token,
	&format!("/{}", dir_name),
	)?;

	if problems.iter().eq(&["A", "B", "C", "D"]) {
	arc_abcd.insert(dir_name);
	} else if problems.iter().eq(&["C", "D", "E", "F"]) {
	arc_cdef.insert(dir_name);
	} else if problems.iter().eq(&["A", "B", "C", "D", "E", "F"]) {
	arc_abcdef.insert(dir_name);
	} else {
	bail!("?????: {:?}", problems);
	}
	}
	}

	if different.is_empty() {
	shell.info("found all")?;
	}

	for (dir_name, contest_id) in different {
	shell.info(format!("not found: {:?} -> {:?}", dir_name, contest_id))?;
	}

	if !arc_abcd.is_empty() {
	for name in arc_abcd {
	shell.info(format!("ARC - A, B, C, D: {:?}", name))?;
	}
	}
	if !arc_cdef.is_empty() {
	for name in arc_cdef {
	shell.info(format!("ARC - C, D, E, F: {:?}", name))?;
	}
	}
	if !arc_abcdef.is_empty() {
	for name in arc_abcdef {
	shell.info(format!("ARC - A, B, C, D, E, F: {:?}", name))?;
	}
	}

	Ok(())
	}

	fn client() -> reqwest::Result<reqwest::blocking::Client> {
	const USER_AGENT: &str = "qryxip@gmail.com";
	const TIMEOUT: Option<Duration> = Some(Duration::from_secs(30));

	reqwest::blocking::ClientBuilder::new()
	.user_agent(USER_AGENT)
	.timeout(TIMEOUT)
	.build()
	}

	fn access_token() -> anyhow::Result<String> {
	env::var("DROPBOX_ACCESS_TOKEN").with_context(\|\| "could not read `$DROPBOX_ACCESS_TOKEN`")
	}

	fn list_folder(
	shell: &mut Shell,
	client: &reqwest::blocking::Client,
	access_token: &str,
	path: &str,
	) -> anyhow::Result<BTreeSet<String>> {
	static SHARED_LINK_URL: &str =
	"https://www.dropbox.com/sh/arnpe0ef5wds8cv/AAAk_SECQ2Nc6SVGii3rHX6Fa?dl=0";

	#[derive(Deserialize)]
	#[serde(untagged)]
	enum ListFolderOutcome {
	Ok(ListFolder),
	Err(serde_json::Value),
	}

	#[derive(Deserialize)]
	struct ListFolder {
	entries: Vec<ListFolderEntry>,
	}

	#[derive(Deserialize)]
	struct ListFolderEntry {
	name: String,
	}

	let res = request_with_message(
	shell,
	client,
	Method::POST,
	"https://api.dropboxapi.com/2/files/list_folder",
	\|req\| {
	req.bearer_auth(access_token)
	.json(&json!({ "shared_link": { "url": SHARED_LINK_URL }, "path": path }))
	},
	)?;

	if res.status() == 200 {
	let ListFolder { entries } = res.json()?;
	Ok(entries
	.into_iter()
	.map(\|ListFolderEntry { name }\| name)
	.collect())
	} else {
	let msg = res.text()?;
	let msg = serde_json::to_string_pretty(&msg).unwrap_or(msg);
	Err(anyhow!("{}", msg).context("API error"))
	}
	}

	fn exists(
	shell: &mut Shell,
	client: &reqwest::blocking::Client,
	contest_id: &str,
	) -> anyhow::Result<bool> {
	let status = request_with_message(
	shell,
	client,
	Method::GET,
	&format!("https://atcoder.jp/contests/{}", contest_id),
	convert::identity,
	)?
	.status();

	match status.as_u16() {
	200 => Ok(true),
	404 => Ok(false),
	_ => bail!("{}", status),
	}
	}

	fn request_with_message(
	shell: &mut Shell,
	client: &reqwest::blocking::Client,
	method: Method,
	url: &str,
	modify_req: impl FnOnce(reqwest::blocking::RequestBuilder) -> reqwest::blocking::RequestBuilder,
	) -> anyhow::Result<reqwest::blocking::Response> {
	let req = modify_req(client.request(method.clone(), url));
	shell.network(format!("{}: {}", method, url))?;
	let res = req.send()?;
	shell.network(res.status())?;
	Ok(res)
	}

	struct Shell(BufferedStandardStream);

	impl Shell {
	fn new() -> Self {
	Self(BufferedStandardStream::stderr(
	if atty::is(atty::Stream::Stderr) {
	ColorChoice::Auto
	} else {
	ColorChoice::Never
	},
	))
	}

	fn info(&mut self, message: impl fmt::Display) -> io::Result<()> {
	self.print("info:", message, Color::Cyan)
	}

	fn network(&mut self, message: impl fmt::Display) -> io::Result<()> {
	self.print("network:", message, Color::Magenta)
	}

	fn print(
	&mut self,
	status: impl fmt::Display,
	message: impl fmt::Display,
	color: Color,
	) -> io::Result<()> {
	self.0
	.set_color(ColorSpec::new().set_bold(true).set_fg(Some(color)))?;
	write!(self.0, "{}", status)?;
	self.0.reset()?;
	writeln!(self.0, " {}", message)?;
	self.0.flush()
	}
	}