// Copyright 2022-2024 The Jujutsu Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Utility for parsing and evaluating user-provided revset expressions.

use std::collections::HashMap;
use std::io;
use std::sync::Arc;

use futures::StreamExt as _;
use futures::TryStreamExt as _;
use futures::stream::LocalBoxStream;
use itertools::Itertools as _;
use jj_lib::backend::CommitId;
use jj_lib::commit::Commit;
use jj_lib::config::ConfigNamePathBuf;
use jj_lib::config::ConfigSource;
use jj_lib::config::StackedConfig;
use jj_lib::id_prefix::IdPrefixContext;
use jj_lib::ref_name::RefNameBuf;
use jj_lib::ref_name::RemoteName;
use jj_lib::ref_name::RemoteNameBuf;
use jj_lib::ref_name::RemoteRefSymbolBuf;
use jj_lib::repo::Repo;
use jj_lib::revset;
use jj_lib::revset::ResolvedRevsetExpression;
use jj_lib::revset::Revset;
use jj_lib::revset::RevsetDiagnostics;
use jj_lib::revset::RevsetEvaluationError;
use jj_lib::revset::RevsetExpression;
use jj_lib::revset::RevsetExtensions;
use jj_lib::revset::RevsetParseContext;
use jj_lib::revset::RevsetParseError;
use jj_lib::revset::RevsetResolutionError;
use jj_lib::revset::RevsetStreamExt as _;
use jj_lib::revset::SymbolResolver;
use jj_lib::revset::SymbolResolverExtension;
use jj_lib::revset::UserRevsetExpression;
use jj_lib::settings::RemoteSettingsMap;
use jj_lib::str_util::StringExpression;
use jj_lib::str_util::StringMatcher;
use thiserror::Error;

use crate::command_error::CommandError;
use crate::command_error::config_error_with_message;
use crate::command_error::print_parse_diagnostics;
use crate::command_error::revset_parse_error_hint;
use crate::command_error::user_error;
use crate::command_error::user_error_with_message;
use crate::formatter::Formatter;
use crate::templater::TemplateRenderer;
use crate::ui::Ui;

const USER_IMMUTABLE_HEADS: &str = "immutable_heads";

#[derive(Debug, Error)]
pub enum UserRevsetEvaluationError {
    #[error(transparent)]
    Resolution(RevsetResolutionError),
    #[error(transparent)]
    Evaluation(RevsetEvaluationError),
}

/// Wrapper around `UserRevsetExpression` to provide convenient methods.
pub struct RevsetExpressionEvaluator<'repo> {
    repo: &'repo dyn Repo,
    extensions: Arc<RevsetExtensions>,
    id_prefix_context: &'repo IdPrefixContext,
    expression: Arc<UserRevsetExpression>,
}

impl<'repo> RevsetExpressionEvaluator<'repo> {
    pub fn new(
        repo: &'repo dyn Repo,
        extensions: Arc<RevsetExtensions>,
        id_prefix_context: &'repo IdPrefixContext,
        expression: Arc<UserRevsetExpression>,
    ) -> Self {
        Self {
            repo,
            extensions,
            id_prefix_context,
            expression,
        }
    }

    /// Returns the underlying expression.
    pub fn expression(&self) -> &Arc<UserRevsetExpression> {
        &self.expression
    }

    /// Intersects the underlying expression with the `other` expression.
    pub fn intersect_with(&mut self, other: &Arc<UserRevsetExpression>) {
        self.expression = self.expression.intersection(other);
    }

    /// Resolves user symbols in the expression, returns new expression.
    pub fn resolve(&self) -> Result<Arc<ResolvedRevsetExpression>, RevsetResolutionError> {
        let symbol_resolver = default_symbol_resolver(
            self.repo,
            self.extensions.symbol_resolvers(),
            self.id_prefix_context,
        );
        self.expression
            .resolve_user_expression(self.repo, &symbol_resolver)
    }

    /// Evaluates the expression.
    pub fn evaluate(&self) -> Result<Box<dyn Revset + 'repo>, UserRevsetEvaluationError> {
        self.resolve()
            .map_err(UserRevsetEvaluationError::Resolution)?
            .evaluate(self.repo)
            .map_err(UserRevsetEvaluationError::Evaluation)
    }

    /// Evaluates the expression to an iterator over commit ids. Entries are
    /// sorted in reverse topological order.
    pub fn evaluate_to_commit_ids(
        &self,
    ) -> Result<
        LocalBoxStream<'repo, Result<CommitId, RevsetEvaluationError>>,
        UserRevsetEvaluationError,
    > {
        Ok(self.evaluate()?.stream())
    }

    /// Evaluates the expression to an iterator over commit objects. Entries are
    /// sorted in reverse topological order.
    pub fn evaluate_to_commits(
        &self,
    ) -> Result<
        LocalBoxStream<'repo, Result<Commit, RevsetEvaluationError>>,
        UserRevsetEvaluationError,
    > {
        Ok(self
            .evaluate()?
            .stream()
            .commits(self.repo.store())
            .boxed_local())
    }
}

pub(super) fn warn_user_redefined_builtin(
    ui: &Ui,
    config: &StackedConfig,
    table_name: &ConfigNamePathBuf,
) -> io::Result<()> {
    let checked_mutability_builtins = ["mutable()", "immutable()", "builtin_immutable_heads()"];
    for layer in config
        .layers()
        .iter()
        .skip_while(|layer| layer.source == ConfigSource::Default)
    {
        let Ok(Some(table)) = layer.look_up_table(table_name) else {
            continue;
        };
        for decl in checked_mutability_builtins
            .iter()
            .filter(|decl| table.contains_key(decl))
        {
            writeln!(
                ui.warning_default(),
                "Redefining `{table_name}.{decl}` is not recommended; redefine \
                 `immutable_heads()` instead.",
            )?;
        }
    }
    Ok(())
}

/// Wraps the given `IdPrefixContext` in `SymbolResolver` to be passed in to
/// `evaluate()`.
pub fn default_symbol_resolver<'a>(
    repo: &'a dyn Repo,
    extensions: &[impl AsRef<dyn SymbolResolverExtension>],
    id_prefix_context: &'a IdPrefixContext,
) -> SymbolResolver<'a> {
    SymbolResolver::new(repo, extensions).with_id_prefix_context(id_prefix_context)
}

/// Parses user-configured expression defining the heads of the immutable set.
/// Includes the root commit.
pub fn parse_immutable_heads_expression(
    diagnostics: &mut RevsetDiagnostics,
    context: &RevsetParseContext,
) -> Result<Arc<UserRevsetExpression>, RevsetParseError> {
    let (_, _, immutable_heads_str, _) = context
        .aliases_map
        .get_function(USER_IMMUTABLE_HEADS, 0)
        .unwrap();
    let heads = revset::parse(diagnostics, immutable_heads_str, context)?;
    Ok(heads.union(&RevsetExpression::root()))
}

/// Parses and resolves `trunk()` alias to detect name resolution error in it.
///
/// Returns `None` if the alias couldn't be parsed. Returns `Err` if the parsed
/// expression had name resolution error.
pub(super) fn try_resolve_trunk_alias(
    repo: &dyn Repo,
    context: &RevsetParseContext,
) -> Result<Option<Arc<ResolvedRevsetExpression>>, RevsetResolutionError> {
    let (_, _, revset_str, _) = context
        .aliases_map
        .get_function("trunk", 0)
        .expect("trunk() should be defined by default");
    let Ok(expression) = revset::parse(&mut RevsetDiagnostics::new(), revset_str, context) else {
        return Ok(None);
    };
    // Not using IdPrefixContext since trunk() revset shouldn't contain short
    // prefixes.
    let symbol_resolver = SymbolResolver::new(repo, context.extensions.symbol_resolvers());
    let resolved = expression.resolve_user_expression(repo, &symbol_resolver)?;
    Ok(Some(resolved))
}

pub(super) async fn evaluate_revset_to_single_commit<'a>(
    revision_str: &str,
    expression: &RevsetExpressionEvaluator<'_>,
    commit_summary_template: impl FnOnce() -> TemplateRenderer<'a, Commit>,
) -> Result<Commit, CommandError> {
    let commits: Vec<_> = expression
        .evaluate_to_commits()?
        .take(6)
        .try_collect()
        .await?;
    match commits.as_slice() {
        [commit] => Ok(commit.clone()),
        [] => Err(user_error(format!(
            "Revset `{revision_str}` didn't resolve to any revisions"
        ))),
        _ => {
            let elided = commits.len() > 5;
            Err(format_multiple_revisions_error(
                revision_str,
                &commits[..std::cmp::min(5, commits.len())],
                elided,
                &commit_summary_template(),
            ))
        }
    }
}

fn format_multiple_revisions_error(
    revision_str: &str,
    commits: &[Commit],
    elided: bool,
    template: &TemplateRenderer<'_, Commit>,
) -> CommandError {
    assert!(commits.len() >= 2);
    let mut cmd_err = user_error(format!(
        "Revset `{revision_str}` resolved to more than one revision"
    ));
    let write_commits_summary = |formatter: &mut dyn Formatter| {
        for commit in commits {
            write!(formatter, "  ")?;
            template.format(commit, formatter)?;
            writeln!(formatter)?;
        }
        if elided {
            writeln!(formatter, "  ...")?;
        }
        Ok(())
    };
    cmd_err.add_formatted_hint_with(|formatter| {
        writeln!(
            formatter,
            "The revset `{revision_str}` resolved to these revisions:"
        )?;
        write_commits_summary(formatter)
    });
    cmd_err
}

#[derive(Debug, Error)]
#[error("Failed to parse bookmark name: {}", source.kind())]
pub struct BookmarkNameParseError {
    pub input: String,
    pub source: RevsetParseError,
}

/// Parses bookmark name specified in revset syntax.
pub fn parse_bookmark_name(text: &str) -> Result<RefNameBuf, BookmarkNameParseError> {
    revset::parse_symbol(text)
        .map(Into::into)
        .map_err(|source| BookmarkNameParseError {
            input: text.to_owned(),
            source,
        })
}

#[derive(Debug, Error)]
#[error("Failed to parse tag name: {}", source.kind())]
pub struct TagNameParseError {
    pub source: RevsetParseError,
}

/// Parses tag name specified in revset syntax.
pub fn parse_tag_name(text: &str) -> Result<RefNameBuf, TagNameParseError> {
    revset::parse_symbol(text)
        .map(Into::into)
        .map_err(|source| TagNameParseError { source })
}

/// Parses bookmark/tag/remote name patterns and unions them all.
pub fn parse_union_name_patterns<I>(ui: &Ui, texts: I) -> Result<StringExpression, CommandError>
where
    I: IntoIterator,
    I::Item: AsRef<str>,
{
    let mut diagnostics = RevsetDiagnostics::new();
    let expressions = texts
        .into_iter()
        .map(|text| revset::parse_string_expression(&mut diagnostics, text.as_ref()))
        .try_collect()
        .map_err(|err| {
            // From<RevsetParseError>, but with different message
            let hint = revset_parse_error_hint(&err);
            let message = format!("Failed to parse name pattern: {}", err.kind());
            let mut cmd_err = user_error_with_message(message, err);
            cmd_err.extend_hints(hint);
            cmd_err
        })?;
    print_parse_diagnostics(ui, "In name pattern", &diagnostics)?;
    Ok(StringExpression::union_all(expressions))
}

/// Parses bookmark/tag name patterns or remote symbols.
pub fn parse_name_patterns_or_remote_symbols<I>(
    ui: &Ui,
    texts: I,
) -> Result<(Vec<StringExpression>, Vec<RemoteRefSymbolBuf>), CommandError>
where
    I: IntoIterator,
    I::Item: AsRef<str>,
{
    let wrap_err = |err| {
        // From<RevsetParseError>, but with different message
        let hint = revset_parse_error_hint(&err);
        let message = format!(
            "Failed to parse name pattern or remote symbol: {}",
            err.kind()
        );
        let mut cmd_err = user_error_with_message(message, err);
        cmd_err.extend_hints(hint);
        cmd_err
    };
    let mut diagnostics = RevsetDiagnostics::new();
    let mut name_expressions = Vec::new();
    let mut remote_symbols = Vec::new();
    for text in texts {
        let node = revset::parse_program(text.as_ref()).map_err(wrap_err)?;
        if let revset::ExpressionKind::RemoteSymbol(symbol) = node.kind {
            remote_symbols.push(symbol);
        } else {
            let expr =
                revset::expect_string_expression(&mut diagnostics, &node).map_err(wrap_err)?;
            name_expressions.push(expr);
        }
    }
    print_parse_diagnostics(ui, "In name pattern", &diagnostics)?;
    Ok((name_expressions, remote_symbols))
}

/// Parses the given `remotes.<name>.auto-track-bookmarks` settings into a map
/// of string matchers.
pub fn parse_remote_auto_track_bookmarks_map(
    ui: &Ui,
    remote_settings: &RemoteSettingsMap,
) -> Result<HashMap<RemoteNameBuf, StringMatcher>, CommandError> {
    let mut matchers = HashMap::new();
    for (name, settings) in remote_settings {
        let Some(text) = &settings.auto_track_bookmarks else {
            continue;
        };
        let expr = parse_remote_string_expression(ui, name, text, "auto-track-bookmarks")?;
        matchers.insert(name.clone(), expr.to_matcher());
    }
    Ok(matchers)
}

/// Parses the given `remotes.<name>.auto-track-bookmarks` and
/// `remotes.<name>.auto-track-created-bookmarks` settings into a map of string
/// matchers. If both settings exist for the same remote, the union of the
/// settings will be matched.
pub fn parse_remote_auto_track_bookmarks_map_for_new_bookmarks(
    ui: &Ui,
    remote_settings: &RemoteSettingsMap,
) -> Result<HashMap<RemoteNameBuf, StringMatcher>, CommandError> {
    let mut matchers = HashMap::new();
    for (name, settings) in remote_settings {
        let mut exprs = Vec::new();
        if let Some(text) = &settings.auto_track_bookmarks {
            exprs.push(parse_remote_string_expression(
                ui,
                name,
                text,
                "auto-track-bookmarks",
            )?);
        }
        if let Some(text) = &settings.auto_track_created_bookmarks {
            exprs.push(parse_remote_string_expression(
                ui,
                name,
                text,
                "auto-track-created-bookmarks",
            )?);
        }
        if exprs.is_empty() {
            continue;
        }
        matchers.insert(
            name.clone(),
            StringExpression::union_all(exprs).to_matcher(),
        );
    }
    Ok(matchers)
}

/// Parses the given `remotes.<name>.fetch-bookmarks` setting.
pub fn parse_remote_fetch_bookmarks(
    ui: &Ui,
    remote_settings: &RemoteSettingsMap,
    name: &RemoteName,
) -> Result<Option<StringExpression>, CommandError> {
    remote_settings
        .get(name)
        .and_then(|settings| settings.fetch_bookmarks.as_ref())
        .map(|text| parse_remote_string_expression(ui, name, text, "fetch-bookmarks"))
        .transpose()
}

/// Parses the given `remotes.<name>.fetch-tags` setting.
pub fn parse_remote_fetch_tags(
    ui: &Ui,
    remote_settings: &RemoteSettingsMap,
    name: &RemoteName,
) -> Result<Option<StringExpression>, CommandError> {
    remote_settings
        .get(name)
        .and_then(|settings| settings.fetch_tags.as_ref())
        .map(|text| parse_remote_string_expression(ui, name, text, "fetch-tags"))
        .transpose()
}

fn parse_remote_string_expression(
    ui: &Ui,
    name: &RemoteName,
    text: &str,
    field_name: &str,
) -> Result<StringExpression, CommandError> {
    let mut diagnostics = RevsetDiagnostics::new();
    let expr = revset::parse_string_expression(&mut diagnostics, text).map_err(|err| {
        // From<RevsetParseError>, but with different message and error kind
        let hint = revset_parse_error_hint(&err);
        let message = format!(
            "Invalid `remotes.{}.{field_name}`: {}",
            name.as_symbol(),
            err.kind()
        );
        let mut cmd_err = config_error_with_message(message, err);
        cmd_err.extend_hints(hint);
        cmd_err
    })?;
    print_parse_diagnostics(
        ui,
        &format!("In `remotes.{}.{field_name}`", name.as_symbol()),
        &diagnostics,
    )?;
    Ok(expr)
}