use std::{ffi::OsString, io};

use anyhow::{anyhow, Context};

use nonempty::NonEmpty;
use radicle::cob::identity::{self, IdentityMut, Revision, RevisionId};
use radicle::identity::{doc, Identity, Visibility};
use radicle::prelude::{Did, Doc, RepoId, Signer};
use radicle::storage::refs;
use radicle::storage::{ReadRepository, ReadStorage as _, WriteRepository};
use radicle::{cob, Profile};
use radicle_crypto::Verified;
use radicle_surf::diff::Diff;
use radicle_term::Element;
use serde_json as json;

use crate::git::unified_diff::Encode as _;
use crate::git::Rev;
use crate::terminal as term;
use crate::terminal::args::{Args, Error, Help};
use crate::terminal::patch::Message;
use crate::terminal::Interactive;

pub const HELP: Help = Help {
    name: "id",
    description: "Manage repository identities",
    version: env!("CARGO_PKG_VERSION"),
    usage: r#"
Usage

    rad id list [<option>...]
    rad id update [--title <string>] [--description <string>]
                  [--delegate <did>] [--rescind <did>]
                  [--threshold <num>] [--visibility <private | public>]
                  [--allow <did>] [--no-confirm] [--payload <id> <key> <val>...]
                  [<option>...]
    rad id edit <revision-id> [--title <string>] [--description <string>] [<option>...]
    rad id show <revision-id> [<option>...]
    rad id <accept | reject | redact> <revision-id> [<option>...]

    The *rad id* command is used to manage and propose changes to the
    identity of a Radicle repository.

    See the rad-id(1) man page for more information.

Options

    --repo <rid>           Repository (defaults to the current repository)
    --quiet, -q            Don't print anything
    --help                 Print help
"#,
};

#[derive(Clone, Debug, Default)]
pub enum Operation {
    Update {
        title: Option<String>,
        description: Option<String>,
        delegate: Vec<Did>,
        rescind: Vec<Did>,
        threshold: Option<usize>,
        visibility: Option<Visibility>,
        payload: Vec<(doc::PayloadId, String, json::Value)>,
    },
    AcceptRevision {
        revision: Rev,
    },
    RejectRevision {
        revision: Rev,
    },
    EditRevision {
        revision: Rev,
        title: Option<String>,
        description: Option<String>,
    },
    RedactRevision {
        revision: Rev,
    },
    ShowRevision {
        revision: Rev,
    },
    #[default]
    ListRevisions,
}

#[derive(Default, PartialEq, Eq)]
pub enum OperationName {
    Accept,
    Reject,
    Edit,
    Update,
    Show,
    Redact,
    #[default]
    List,
}

pub struct Options {
    pub op: Operation,
    pub rid: Option<RepoId>,
    pub interactive: Interactive,
    pub quiet: bool,
}

impl Args for Options {
    fn from_args(args: Vec<OsString>) -> anyhow::Result<(Self, Vec<OsString>)> {
        use lexopt::prelude::*;

        let mut parser = lexopt::Parser::from_args(args);
        let mut op: Option<OperationName> = None;
        let mut revision: Option<Rev> = None;
        let mut rid: Option<RepoId> = None;
        let mut title: Option<String> = None;
        let mut description: Option<String> = None;
        let mut delegate: Vec<Did> = Vec::new();
        let mut rescind: Vec<Did> = Vec::new();
        let mut visibility: Option<Visibility> = None;
        let mut threshold: Option<usize> = None;
        let mut interactive = Interactive::new(io::stdout());
        let mut payload = Vec::new();
        let mut quiet = false;

        while let Some(arg) = parser.next()? {
            match arg {
                Long("help") => {
                    return Err(Error::HelpManual { name: "rad-id" }.into());
                }
                Short('h') => {
                    return Err(Error::Help.into());
                }
                Long("title")
                    if op == Some(OperationName::Edit) || op == Some(OperationName::Update) =>
                {
                    title = Some(parser.value()?.to_string_lossy().into());
                }
                Long("description")
                    if op == Some(OperationName::Edit) || op == Some(OperationName::Update) =>
                {
                    description = Some(parser.value()?.to_string_lossy().into());
                }
                Long("quiet") | Short('q') => {
                    quiet = true;
                }
                Long("no-confirm") => {
                    interactive = Interactive::No;
                }
                Value(val) if op.is_none() => match val.to_string_lossy().as_ref() {
                    "e" | "edit" => op = Some(OperationName::Edit),
                    "u" | "update" => op = Some(OperationName::Update),
                    "l" | "list" => op = Some(OperationName::List),
                    "s" | "show" => op = Some(OperationName::Show),
                    "a" | "accept" => op = Some(OperationName::Accept),
                    "r" | "reject" => op = Some(OperationName::Reject),
                    "d" | "redact" => op = Some(OperationName::Redact),

                    unknown => anyhow::bail!("unknown operation '{}'", unknown),
                },
                Long("repo") => {
                    let val = parser.value()?;
                    let val = term::args::rid(&val)?;

                    rid = Some(val);
                }
                Long("delegate") => {
                    let did = term::args::did(&parser.value()?)?;
                    delegate.push(did);
                }
                Long("rescind") => {
                    let did = term::args::did(&parser.value()?)?;
                    rescind.push(did);
                }
                Long("allow") => {
                    let value = parser.value()?;
                    let did = term::args::did(&value)?;
                    if let Some(Visibility::Private { allow }) = &mut visibility {
                        allow.insert(did);
                    } else {
                        visibility = Some(Visibility::private([did]));
                    }
                }
                Long("visibility") => {
                    let value = parser.value()?;
                    let value = term::args::parse_value("visibility", value)?;

                    visibility = Some(value);
                }
                Long("threshold") => {
                    threshold = Some(parser.value()?.to_string_lossy().parse()?);
                }
                Long("payload") => {
                    let mut values = parser.values()?;
                    let id = values
                        .next()
                        .ok_or(anyhow!("expected payload id, eg. `xyz.radicle.project`"))?;
                    let id: doc::PayloadId = term::args::parse_value("payload", id)?;

                    let key = values
                        .next()
                        .ok_or(anyhow!("expected payload key, eg. 'defaultBranch'"))?;
                    let key = term::args::string(&key);

                    let val = values
                        .next()
                        .ok_or(anyhow!("expected payload value, eg. '\"heartwood\"'"))?;
                    let val = val.to_string_lossy().to_string();
                    let val = json::from_str(val.as_str())
                        .map_err(|e| anyhow!("invalid JSON value `{val}`: {e}"))?;

                    payload.push((id, key, val));
                }
                Value(val) => {
                    let val = term::args::rev(&val)?;
                    revision = Some(val);
                }
                _ => {
                    return Err(anyhow!(arg.unexpected()));
                }
            }
        }

        let op = match op.unwrap_or_default() {
            OperationName::Accept => Operation::AcceptRevision {
                revision: revision.ok_or_else(|| anyhow!("a revision must be provided"))?,
            },
            OperationName::Reject => Operation::RejectRevision {
                revision: revision.ok_or_else(|| anyhow!("a revision must be provided"))?,
            },
            OperationName::Edit => Operation::EditRevision {
                title,
                description,
                revision: revision.ok_or_else(|| anyhow!("a revision must be provided"))?,
            },
            OperationName::Show => Operation::ShowRevision {
                revision: revision.ok_or_else(|| anyhow!("a revision must be provided"))?,
            },
            OperationName::List => Operation::ListRevisions,
            OperationName::Redact => Operation::RedactRevision {
                revision: revision.ok_or_else(|| anyhow!("a revision must be provided"))?,
            },
            OperationName::Update => Operation::Update {
                title,
                description,
                delegate,
                rescind,
                threshold,
                visibility,
                payload,
            },
        };
        Ok((
            Options {
                rid,
                op,
                interactive,
                quiet,
            },
            vec![],
        ))
    }
}

pub fn run(options: Options, ctx: impl term::Context) -> anyhow::Result<()> {
    let profile = ctx.profile()?;
    let signer = term::signer(&profile)?;
    let storage = &profile.storage;
    let rid = if let Some(rid) = options.rid {
        rid
    } else {
        let (_, rid) = radicle::rad::cwd()?;
        rid
    };
    let repo = storage
        .repository(rid)
        .context(anyhow!("repository `{rid}` not found in local storage"))?;
    let mut identity = Identity::load_mut(&repo)?;
    let current = identity.current().clone();

    match options.op {
        Operation::AcceptRevision { revision } => {
            let revision = get(revision, &identity, &repo)?.clone();
            let id = revision.id;

            if !revision.is_active() {
                anyhow::bail!("cannot vote on revision that is {}", revision.state);
            }

            if options
                .interactive
                .confirm(format!("Accept revision {}?", term::format::tertiary(id)))
            {
                identity.accept(&revision.id, &signer)?;

                if let Some(revision) = identity.revision(&id) {
                    // Update the canonical head to point to the latest accepted revision.
                    if revision.is_accepted() && revision.id == identity.current {
                        repo.set_identity_head_to(revision.id)?;
                    }
                    // TODO: Different output if canonical changed?

                    if !options.quiet {
                        term::success!("Revision {id} accepted");
                        print_meta(revision, &current, &profile)?;
                    }
                }
            }
        }
        Operation::RejectRevision { revision } => {
            let revision = get(revision, &identity, &repo)?.clone();

            if !revision.is_active() {
                anyhow::bail!("cannot vote on revision that is {}", revision.state);
            }

            if options.interactive.confirm(format!(
                "Reject revision {}?",
                term::format::tertiary(revision.id)
            )) {
                identity.reject(revision.id, &signer)?;

                if !options.quiet {
                    term::success!("Revision {} rejected", revision.id);
                    print_meta(&revision, &current, &profile)?;
                }
            }
        }
        Operation::EditRevision {
            revision,
            title,
            description,
        } => {
            let revision = get(revision, &identity, &repo)?.clone();

            if !revision.is_active() {
                anyhow::bail!("revision can no longer be edited");
            }
            let Some((title, description)) = edit_title_description(title, description)? else {
                anyhow::bail!("revision title or description missing");
            };
            identity.edit(revision.id, title, description, &signer)?;

            if !options.quiet {
                term::success!("Revision {} edited", revision.id);
            }
        }
        Operation::Update {
            title,
            description,
            delegate: delegates,
            rescind,
            threshold,
            visibility,
            payload,
        } => {
            let proposal = {
                let mut proposal = current.doc.clone();
                proposal.threshold = threshold.unwrap_or(proposal.threshold);
                proposal.visibility = visibility.unwrap_or(proposal.visibility);
                proposal.delegates = NonEmpty::from_vec(
                    proposal
                        .delegates
                        .into_iter()
                        .chain(delegates)
                        .filter(|d| !rescind.contains(d))
                        .collect::<Vec<_>>(),
                )
                .ok_or(anyhow!(
                    "at lease one delegate must be present for the identity to be valid"
                ))?;

                if let Some(errs) = verify_delegates(&proposal.delegates, &repo)? {
                    term::error(format!("failed to verify delegates for {rid}"));
                    for e in errs {
                        e.print();
                    }
                    anyhow::bail!("fatal: refusing to update identity document");
                }

                for (id, key, val) in payload {
                    if let Some(ref mut payload) = proposal.payload.get_mut(&id) {
                        if let Some(obj) = payload.as_object_mut() {
                            obj.insert(key, val);
                        } else {
                            anyhow::bail!("payload `{id}` is not a map");
                        }
                    } else {
                        anyhow::bail!("payload `{id}` not found in identity document");
                    }
                }
                proposal
            };
            if proposal == current.doc {
                return Err(Error::WithHint {
                    err: anyhow!("no update specified"),
                    hint: "an update to the identity must be specified, run `rad id update -h` to see the available options"
                }.into());
            }
            let revision = update(title, description, proposal, &mut identity, &signer)?;

            if revision.is_accepted() && revision.parent == Some(current.id) {
                // Update the canonical head to point to the latest accepted revision.
                repo.set_identity_head_to(revision.id)?;
            }
            if options.quiet {
                term::print(revision.id);
            } else {
                term::success!(
                    "Identity revision {} created",
                    term::format::tertiary(revision.id)
                );
                print(&revision, &current, &repo, &profile)?;
            }
        }
        Operation::ListRevisions => {
            let mut revisions =
                term::Table::<7, term::Label>::new(term::table::TableOptions::bordered());

            revisions.push([
                term::format::dim(String::from("●")).into(),
                term::format::bold(String::from("ID")).into(),
                term::format::bold(String::from("Title")).into(),
                term::format::bold(String::from("Author")).into(),
                term::Label::blank(),
                term::format::bold(String::from("Status")).into(),
                term::format::bold(String::from("Created")).into(),
            ]);
            revisions.divider();

            for r in identity.revisions().rev() {
                let icon = match r.state {
                    identity::State::Active => term::format::tertiary("●"),
                    identity::State::Accepted => term::format::positive("●"),
                    identity::State::Rejected => term::format::negative("●"),
                    identity::State::Stale => term::format::dim("●"),
                }
                .into();
                let state = r.state.to_string().into();
                let id = term::format::oid(r.id).into();
                let title = term::label(r.title.to_string());
                let (alias, author) =
                    term::format::Author::new(r.author.public_key(), &profile).labels();
                let timestamp = term::format::timestamp(r.timestamp).into();

                revisions.push([icon, id, title, alias, author, state, timestamp]);
            }
            revisions.print();
        }
        Operation::RedactRevision { revision } => {
            let revision = get(revision, &identity, &repo)?.clone();

            if revision.is_accepted() {
                anyhow::bail!("cannot redact accepted revision");
            }
            if options.interactive.confirm(format!(
                "Redact revision {}?",
                term::format::tertiary(revision.id)
            )) {
                identity.redact(revision.id, &signer)?;

                if !options.quiet {
                    term::success!("Revision {} redacted", revision.id);
                }
            }
        }
        Operation::ShowRevision { revision } => {
            let revision = get(revision, &identity, &repo)?;
            print(revision, &current, &repo, &profile)?;
        }
    }
    Ok(())
}

fn get<'a>(
    revision: Rev,
    identity: &'a Identity,
    repo: &radicle::storage::git::Repository,
) -> anyhow::Result<&'a Revision> {
    let id = revision.resolve(&repo.backend)?;
    let revision = identity
        .revision(&id)
        .ok_or(anyhow!("revision `{id}` not found"))?;

    Ok(revision)
}

fn print_meta(
    revision: &Revision,
    previous: &Doc<Verified>,
    profile: &Profile,
) -> anyhow::Result<()> {
    let mut attrs = term::Table::<2, term::Label>::new(Default::default());

    attrs.push([
        term::format::bold("Title").into(),
        term::label(revision.title.to_owned()),
    ]);
    attrs.push([
        term::format::bold("Revision").into(),
        term::label(revision.id.to_string()),
    ]);
    attrs.push([
        term::format::bold("Blob").into(),
        term::label(revision.blob.to_string()),
    ]);
    attrs.push([
        term::format::bold("Author").into(),
        term::label(revision.author.to_string()),
    ]);
    attrs.push([
        term::format::bold("State").into(),
        term::label(revision.state.to_string()),
    ]);
    attrs.push([
        term::format::bold("Quorum").into(),
        if revision.is_accepted() {
            term::format::positive("yes").into()
        } else {
            term::format::negative("no").into()
        },
    ]);

    let mut meta = term::VStack::default()
        .border(Some(term::colors::FAINT))
        .child(attrs)
        .children(if !revision.description.is_empty() {
            vec![
                term::Label::blank().boxed(),
                term::textarea(revision.description.to_owned()).boxed(),
            ]
        } else {
            vec![]
        })
        .divider();

    let accepted = revision.accepted().collect::<Vec<_>>();
    let rejected = revision.rejected().collect::<Vec<_>>();
    let unknown = previous
        .delegates
        .iter()
        .filter(|id| !accepted.contains(id) && !rejected.contains(id))
        .collect::<Vec<_>>();
    let mut signatures = term::Table::<4, _>::default();

    for id in accepted {
        let author = term::format::Author::new(&id, profile);
        signatures.push([
            term::format::positive("✓").into(),
            id.to_string().into(),
            author.alias().unwrap_or_default(),
            author.you().unwrap_or_default(),
        ]);
    }
    for id in rejected {
        let author = term::format::Author::new(&id, profile);
        signatures.push([
            term::format::negative("✗").into(),
            id.to_string().into(),
            author.alias().unwrap_or_default(),
            author.you().unwrap_or_default(),
        ]);
    }
    for id in unknown {
        let author = term::format::Author::new(id, profile);
        signatures.push([
            term::format::dim("?").into(),
            id.to_string().into(),
            author.alias().unwrap_or_default(),
            author.you().unwrap_or_default(),
        ]);
    }
    meta.push(signatures);
    meta.print();

    Ok(())
}

fn print(
    revision: &identity::Revision,
    previous: &identity::Revision,
    repo: &radicle::storage::git::Repository,
    profile: &Profile,
) -> anyhow::Result<()> {
    print_meta(revision, previous, profile)?;
    println!();
    print_diff(revision.parent.as_ref(), &revision.id, repo)?;

    Ok(())
}

fn edit_title_description(
    title: Option<String>,
    description: Option<String>,
) -> anyhow::Result<Option<(String, String)>> {
    const HELP: &str = r#"<!--
Please enter a patch message for your changes. An empty
message aborts the patch proposal.

The first line is the patch title. The patch description
follows, and must be separated with a blank line, just
like a commit message. Markdown is supported in the title
and description.
-->"#;

    let result = if let (Some(t), Some(d)) = (title.as_ref(), description.as_ref()) {
        Some((t.to_owned(), d.to_owned()))
    } else {
        let result = Message::edit_title_description(title, description, HELP)?;
        if let Some((title, description)) = result {
            Some((title, description))
        } else {
            None
        }
    };
    Ok(result)
}

fn update<R: WriteRepository + cob::Store, G: Signer>(
    title: Option<String>,
    description: Option<String>,
    doc: Doc<Verified>,
    current: &mut IdentityMut<R>,
    signer: &G,
) -> anyhow::Result<Revision> {
    if let Some((title, description)) = edit_title_description(title, description)? {
        let id = current.update(title, description, &doc, signer)?;
        let revision = current
            .revision(&id)
            .ok_or(anyhow!("update failed: revision {id} is missing"))?;

        Ok(revision.clone())
    } else {
        Err(anyhow!("you must provide a revision title and description"))
    }
}

fn print_diff(
    previous: Option<&RevisionId>,
    current: &RevisionId,
    repo: &radicle::storage::git::Repository,
) -> anyhow::Result<()> {
    let previous = if let Some(previous) = previous {
        let previous = Doc::<Verified>::load_at(*previous, repo)?;
        let previous = serde_json::to_string_pretty(&previous.doc)?;

        Some(previous)
    } else {
        None
    };
    let current = Doc::<Verified>::load_at(*current, repo)?;
    let current = serde_json::to_string_pretty(&current.doc)?;

    let tmp = tempfile::tempdir()?;
    let repo = radicle::git::raw::Repository::init_bare(tmp.path())?;

    let previous = if let Some(previous) = previous {
        let tree = radicle::git::write_tree(&doc::PATH, previous.as_bytes(), &repo)?;
        Some(tree)
    } else {
        None
    };
    let current = radicle::git::write_tree(&doc::PATH, current.as_bytes(), &repo)?;
    let mut opts = radicle::git::raw::DiffOptions::new();
    opts.context_lines(u32::MAX);

    let diff = repo.diff_tree_to_tree(previous.as_ref(), Some(&current), Some(&mut opts))?;
    let diff = Diff::try_from(diff)?;

    if let Some(modified) = diff.modified().next() {
        let diff = modified.diff.to_unified_string()?;
        print!("{diff}");
    } else {
        term::print(term::format::italic("No changes."));
    }
    Ok(())
}

enum VerificationError {
    Missing(Did),
    MissingDefaultBranch {
        branch: radicle::git::RefString,
        did: Did,
    },
}

impl VerificationError {
    fn print(&self) {
        match self {
            VerificationError::Missing(did) => term::error(format!(
                "missing delegate {} in local storage",
                term::format::did(did)
            )),
            VerificationError::MissingDefaultBranch { branch, did } => term::error(format!(
                "missing {} for {} in local storage",
                term::format::secondary(branch),
                term::format::did(did)
            )),
        }
    }
}

fn verify_delegates<S>(
    dids: &NonEmpty<Did>,
    repo: &S,
) -> anyhow::Result<Option<Vec<VerificationError>>>
where
    S: ReadRepository,
{
    let (canonical, _) = repo.canonical_head()?;
    let mut errors = Vec::with_capacity(dids.len());
    for did in dids {
        match refs::SignedRefsAt::load((*did).into(), repo)? {
            None => {
                errors.push(VerificationError::Missing(*did));
            }
            Some(refs::SignedRefsAt { sigrefs, .. }) => {
                if sigrefs.get(&canonical).is_none() {
                    errors.push(VerificationError::MissingDefaultBranch {
                        branch: canonical.to_ref_string(),
                        did: *did,
                    })
                }
            }
        }
    }
    Ok((!errors.is_empty()).then_some(errors))
}