// Copyright 2016 Kitware, Inc.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use crates::itertools::Itertools;
use crates::regex::Regex;

use impl_prelude::*;

#[derive(Debug, Default, Clone)]
/// Check commit message subjects for invalid patterns.
pub struct CommitSubject {
    /// The minimum length allowed for the summary line.
    min_summary: usize,
    /// The maximum length allowed for the summary line.
    max_summary: usize,

    /// Whether to deny work-in-progress commits or not.
    check_wip: bool,

    /// Whether to deny `fixup!` and `squash!` commits or not.
    check_rebase_commands: bool,

    /// Tolerated prefixes for commits.
    tolerated_prefixes: Vec<Regex>,
    /// Required prefixes for commits.
    allowed_prefixes: Vec<String>,
    /// Forbidden prefixes for commits.
    disallowed_prefixes: Vec<String>,
}

impl CommitSubject {
    /// Checks commit message subjects for invalid patterns
    ///
    /// Patterns which are checked for:
    ///   - overly long or short summary lines;
    ///   - work-in-progress messages;
    ///   - `fixup!` and `squash!` messages; and
    ///   - custom prefixes.
    ///
    /// Commit messages which appear to have been auto generated by actions such as merging or
    /// reverting commits will skip the summary line length limit (if enforced).
    pub fn new() -> Self {
        Self {
            min_summary: 8,
            max_summary: 78,

            check_wip: true,

            check_rebase_commands: true,

            tolerated_prefixes: Vec::new(),
            allowed_prefixes: Vec::new(),
            disallowed_prefixes: Vec::new(),
        }
    }

    /// Check the summary line with the given limits.
    pub fn with_summary_limits(&mut self, min: usize, max: usize) -> &mut Self {
        self.min_summary = min;
        self.max_summary = max;
        self
    }

    /// Checks for work-in-progress commits
    ///
    /// Commit messages which mention `WIP` or `wip` at the beginning of their commit messages are
    /// rejected since they are (nominally) incomplete.
    pub fn check_work_in_progress(&mut self, wip: bool) -> &mut Self {
        self.check_wip = wip;
        self
    }

    /// Check for rebase commands
    ///
    /// Rebase commands include commits which begin with `fixup! ` or `squash! `. These subjects
    /// are used to indicate that the commit belongs somewhere else in the branch and should be
    /// completed before merging.
    pub fn check_rebase_commands(&mut self, rebase: bool) -> &mut Self {
        self.check_rebase_commands = rebase;
        self
    }

    /// Check for tolerated commit subject prefixes.
    ///
    /// The specified prefix patterns will be tolerated regardless of any configured
    /// allowed or disallowed prefixes.
    pub fn with_tolerated_prefixes<I, P>(&mut self, patterns: I) -> &mut Self
    where
        I: IntoIterator<Item = P>,
        P: Into<Regex>,
    {
        self.tolerated_prefixes
            .extend(patterns.into_iter().map(Into::into));
        self
    }

    /// Check for required commit prefixes.
    ///
    /// The specified prefixes will be the only allowed prefixes on commit message subjects
    /// that do not match a tolerated pattern.
    pub fn with_allowed_prefixes<I, P>(&mut self, prefixes: I) -> &mut Self
    where
        I: IntoIterator<Item = P>,
        P: Into<String>,
    {
        self.allowed_prefixes
            .extend(prefixes.into_iter().map(Into::into));
        self
    }

    /// Check for disallowed commit prefixes.
    ///
    /// The specified prefixes will be rejected on commit message subjects that do not
    /// also match a tolerated pattern.
    pub fn with_disallowed_prefixes<I, P>(&mut self, prefixes: I) -> &mut Self
    where
        I: IntoIterator<Item = P>,
        P: Into<String>,
    {
        self.disallowed_prefixes
            .extend(prefixes.into_iter().map(Into::into));
        self
    }

    /// Whether the summary is generated or not.
    ///
    /// The commit summaries generated by `git merge` and `git revert` can be long, but since they
    /// are auto-generated, allow them.
    fn is_generated_subject(summary: &str) -> bool {
        false || // rustfmt break
            summary.starts_with("Merge ") || // rustfmt break
            summary.starts_with("Revert ")
    }
}

impl Check for CommitSubject {
    fn name(&self) -> &str {
        "commit-subject"
    }

    fn check(&self, _: &CheckGitContext, commit: &Commit) -> Result<CheckResult> {
        let mut result = CheckResult::new();
        let lines = commit.message.trim().lines().collect::<Vec<_>>();

        if lines.is_empty() {
            result.add_error(format!(
                "commit {} has an invalid commit subject; it is empty.",
                commit.sha1
            ));
            return Ok(result);
        }

        let summary = &lines[0];
        let summary_len = summary.len();

        if summary_len < self.min_summary {
            result.add_error(format!(
                "commit {} has an invalid commit subject; the first line \
                 must be at least {} characters.",
                commit.sha1, self.min_summary
            ));
        }

        let is_generated = Self::is_generated_subject(summary);
        if !is_generated && self.max_summary < summary_len {
            result.add_error(format!(
                "commit {} has an invalid commit subject; the first line \
                 must be no longer than {} characters.",
                commit.sha1, self.max_summary
            ));
        }

        if lines.len() >= 2 {
            if lines.len() >= 2 && !lines[1].is_empty() {
                result.add_error(format!(
                    "commit {} has an invalid commit subject; the second \
                     line must be empty.",
                    commit.sha1
                ));
            }

            if lines.len() == 2 {
                result.add_error(format!(
                    "commit {} has an invalid commit subject; it cannot be \
                     exactly two lines.",
                    commit.sha1
                ));
            } else if lines[2].is_empty() {
                result.add_error(format!(
                    "commit {} has an invalid commit subject; the third \
                     line must not be empty.",
                    commit.sha1
                ));
            }
        }

        if self.check_wip && (summary.starts_with("WIP") || summary.starts_with("wip")) {
            result.add_error(format!(
                "commit {} cannot be merged; it is marked as a \
                 work-in-progress (WIP).",
                commit.sha1
            ));
        }

        if self.check_rebase_commands {
            if summary.starts_with("fixup! ") {
                result.add_error(format!(
                    "commit {} cannot be merged; it is marked as a fixup \
                     commit.",
                    commit.sha1
                ));
            } else if summary.starts_with("squash! ") {
                result.add_error(format!(
                    "commit {} cannot be merged; it is marked as a commit \
                     to be squashed.",
                    commit.sha1
                ));
            }
        }

        if !is_generated {
            let is_tolerated = self.tolerated_prefixes.iter().any(|regex| {
                regex
                    .find(summary)
                    .map(|found| found.start() == 0)
                    .unwrap_or(false)
            });
            if !is_tolerated {
                if !self.allowed_prefixes.is_empty() {
                    let is_ok = self
                        .allowed_prefixes
                        .iter()
                        .any(|prefix| summary.starts_with(prefix));
                    if !is_ok {
                        result.add_error(format!(
                            "commit {} cannot be merged; it must start with one \
                             of the following prefixes: `{}`.",
                            commit.sha1,
                            self.allowed_prefixes.iter().format("`, `")
                        ));
                    }
                }

                let is_ok = self
                    .disallowed_prefixes
                    .iter()
                    .all(|prefix| !summary.starts_with(prefix));
                if !is_ok {
                    result.add_error(format!(
                        "commit {} cannot be merged; it cannot start with \
                         any of the following prefixes: `{}`.",
                        commit.sha1,
                        self.disallowed_prefixes.iter().format("`, `")
                    ));
                }
            }
        }

        Ok(result)
    }
}

#[cfg(test)]
mod tests {
    use checks::test::*;
    use checks::CommitSubject;
    use crates::regex::Regex;

    const BAD_TOPIC: &str = "5f7284fe1599265c90550b681a4bf0763bc1de21";

    #[test]
    fn test_check_subject() {
        let check = CommitSubject::new();
        let result = run_check("test_check_subject", BAD_TOPIC, check);
        test_result_errors(result, &[
            "commit 234de3c3f17ab29f0b7644ae96242e31a3dd634c has an invalid commit subject; the \
             first line must be at least 8 characters.",
            "commit 1afc6b3584580488917fc61aa5e5298e98583805 has an invalid commit subject; the \
             first line must be no longer than 78 characters.",
            "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 has an invalid commit subject; the \
             second line must be empty.",
            "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 has an invalid commit subject; it \
             cannot be exactly two lines.",
            "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 has an invalid commit subject; the \
             second line must be empty.",
            "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 has an invalid commit subject; the \
             third line must not be empty.",
            "commit e478f630b586e331753477eba88059d644927be8 cannot be merged; it is marked as a \
             work-in-progress (WIP).",
            "commit 9039b9a4813fa019229e960033fe1ae8514a0c8e cannot be merged; it is marked as a \
             work-in-progress (WIP).",
            "commit 11dbbbff3f32445d74d1a8d96df0a49381c81ba0 cannot be merged; it is marked as a \
             work-in-progress (WIP).",
            "commit 54d673ff559a72ce6343bd9526a950d79034b24e cannot be merged; it is marked as a \
             fixup commit.",
            "commit 5f7284fe1599265c90550b681a4bf0763bc1de21 cannot be merged; it is marked as a \
             commit to be squashed.",
        ]);
    }

    #[test]
    fn test_check_subject_allowed_prefixes() {
        let mut check = CommitSubject::new();
        check
            .check_work_in_progress(false)
            .check_rebase_commands(false)
            .with_allowed_prefixes(vec!["commit message "]);
        let result = run_check("test_check_subject_allowed_prefixes", BAD_TOPIC, check);
        test_result_errors(result, &[
            "commit 234de3c3f17ab29f0b7644ae96242e31a3dd634c has an invalid commit subject; the \
             first line must be at least 8 characters.",
            "commit 234de3c3f17ab29f0b7644ae96242e31a3dd634c cannot be merged; it must start with one of the following prefixes: `commit message `.",
            "commit 1afc6b3584580488917fc61aa5e5298e98583805 has an invalid commit subject; the \
             first line must be no longer than 78 characters.",
            "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 has an invalid commit subject; the \
             second line must be empty.",
            "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 has an invalid commit subject; it \
             cannot be exactly two lines.",
            "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 has an invalid commit subject; the \
             second line must be empty.",
            "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 has an invalid commit subject; the \
             third line must not be empty.",
            "commit e478f630b586e331753477eba88059d644927be8 cannot be merged; it must start with \
             one of the following prefixes: `commit message `.",
            "commit 9039b9a4813fa019229e960033fe1ae8514a0c8e cannot be merged; it must start with \
             one of the following prefixes: `commit message `.",
            "commit 11dbbbff3f32445d74d1a8d96df0a49381c81ba0 cannot be merged; it must start with \
             one of the following prefixes: `commit message `.",
            "commit 54d673ff559a72ce6343bd9526a950d79034b24e cannot be merged; it must start with \
             one of the following prefixes: `commit message `.",
            "commit 5f7284fe1599265c90550b681a4bf0763bc1de21 cannot be merged; it must start with \
             one of the following prefixes: `commit message `.",
        ]);
    }

    #[test]
    fn test_check_subject_disallowed_prefixes() {
        let mut check = CommitSubject::new();
        check
            .check_work_in_progress(false)
            .check_rebase_commands(false)
            .with_disallowed_prefixes(vec!["commit message "]);
        let result = run_check("test_check_subject_disallowed_prefixes", BAD_TOPIC, check);
        test_result_errors(result, &[
            "commit 234de3c3f17ab29f0b7644ae96242e31a3dd634c has an invalid commit subject; the \
             first line must be at least 8 characters.",
            "commit 1afc6b3584580488917fc61aa5e5298e98583805 has an invalid commit subject; the \
             first line must be no longer than 78 characters.",
            "commit 1afc6b3584580488917fc61aa5e5298e98583805 cannot be merged; it cannot start \
             with any of the following prefixes: `commit message `.",
            "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 has an invalid commit subject; the \
             second line must be empty.",
            "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 has an invalid commit subject; it \
             cannot be exactly two lines.",
            "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 cannot be merged; it cannot start \
             with any of the following prefixes: `commit message `.",
            "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 has an invalid commit subject; the \
             second line must be empty.",
            "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 has an invalid commit subject; the \
             third line must not be empty.",
            "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 cannot be merged; it cannot start \
             with any of the following prefixes: `commit message `.",
        ]);
    }

    #[test]
    fn test_check_subject_tolerated_prefixes() {
        let mut check = CommitSubject::new();
        check
            .check_work_in_progress(false)
            .check_rebase_commands(false)
            .with_tolerated_prefixes(vec![
                Regex::new("^(commit message )").unwrap(),
                Regex::new("^([Ww][Ii][Pp]|fixup|squash)").unwrap(),
                // Intentionally match the middle of commit 234de3c3f's subject line
                // to verify that the line "short" is not a tolerated prefix.
                Regex::new("hort").unwrap(),
            ]).with_allowed_prefixes(vec!["allowed prefix "])
            .with_disallowed_prefixes(vec!["commit message "]);
        let result = run_check("test_check_subject_tolerated_prefixes", BAD_TOPIC, check);
        test_result_errors(
            result,
            &[
                "commit 234de3c3f17ab29f0b7644ae96242e31a3dd634c has an invalid commit subject; \
                 the first line must be at least 8 characters.",
                "commit 234de3c3f17ab29f0b7644ae96242e31a3dd634c cannot be merged; it must start \
                 with one of the following prefixes: `allowed prefix `.",
                "commit 1afc6b3584580488917fc61aa5e5298e98583805 has an invalid commit subject; \
                 the first line must be no longer than 78 characters.",
                "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 has an invalid commit subject; \
                 the second line must be empty.",
                "commit b1ca628043ed78625551420e2dbbd8cf74fde2c4 has an invalid commit subject; \
                 it cannot be exactly two lines.",
                "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 has an invalid commit subject; \
                 the second line must be empty.",
                "commit 3a6fe6d56fbf11c667b6c88bdd7d851a8dcac0b1 has an invalid commit subject; \
                 the third line must not be empty.",
            ],
        );
    }
}