use cuddle_please_frontend::PleaseConfig;

use ::semver::Version;
use anyhow::Context;

use cuddle_please_misc::{
    changelog_parser, get_most_significant_version, ChangeLogBuilder, Commit, DynRemoteGitClient,
    DynUi, NextVersion, Tag, VcsClient,
};

pub struct ReleaseCommandHandler {
    ui: DynUi,
    config: PleaseConfig,
    git_client: VcsClient,
    gitea_client: DynRemoteGitClient,
}

impl ReleaseCommandHandler {
    pub fn new(
        ui: DynUi,
        config: PleaseConfig,
        git_client: VcsClient,
        gitea_client: DynRemoteGitClient,
    ) -> Self {
        Self {
            ui,
            config,
            git_client,
            gitea_client,
        }
    }

    pub fn execute(&self, dry_run: bool) -> anyhow::Result<()> {
        tracing::debug!("running command: release");
        let owner = self.config.get_owner();
        let repository = self.config.get_repository();
        let branch = self.config.get_branch();
        let source = self.config.get_source();

        self.ui.write_str_ln("running releaser");

        self.check_git_remote_connection(owner, repository)?;
        tracing::trace!("connected to git remote");

        let significant_tag = self.get_most_significant_tag(owner, repository)?;
        tracing::trace!("found lastest release tag");

        let commits =
            self.fetch_commits_since_last_tag(owner, repository, &significant_tag, branch)?;
        tracing::trace!("fetched commits since last version");
        let current_version = get_current_version(significant_tag);
        tracing::trace!("found current version: {}", current_version.to_string());
        self.ui
            .write_str_ln(&format!("found current version: {}", current_version));

        let conventional_commit_results = parse_conventional_commits(current_version, commits)?;
        tracing::trace!("parsing conventional commits");
        if conventional_commit_results.is_none() {
            tracing::debug!("found no new commits, aborting early");
            self.ui
                .write_str_ln("no new commits found, no release required");
            return Ok(());
        }
        let (commit_strs, next_version) = conventional_commit_results.unwrap();
        self.ui
            .write_str_ln(&format!("calculated next version: {}", next_version));

        tracing::trace!("creating changelog");
        let (changelog_placement, changelog, changelog_last_changes) =
            compose_changelog(&commit_strs, &next_version, source)?;

        if let Some(first_commit) = commit_strs.first() {
            if first_commit.contains("chore(release): ") {
                tracing::trace!("creating release");
                self.ui.write_str_ln("creating release");
                self.create_release(
                    dry_run,
                    owner,
                    repository,
                    &next_version,
                    changelog_last_changes,
                )?;

                return Ok(());
            }
        }

        tracing::trace!("creating pull-request");
        self.create_pull_request(
            changelog_placement,
            changelog,
            next_version,
            dry_run,
            owner,
            repository,
            changelog_last_changes,
            branch,
        )?;

        Ok(())
    }

    fn create_release(
        &self,
        dry_run: bool,
        owner: &str,
        repository: &str,
        next_version: &Version,
        changelog_last_changes: Option<String>,
    ) -> Result<(), anyhow::Error> {
        if !dry_run {
            self.gitea_client.create_release(
                owner,
                repository,
                &next_version.to_string(),
                &changelog_last_changes.unwrap(),
                !next_version.pre.is_empty(),
            )?;
        } else {
            tracing::debug!("creating release (dry_run)");
        };
        Ok(())
    }

    fn create_pull_request(
        &self,
        changelog_placement: std::path::PathBuf,
        changelog: String,
        next_version: Version,
        dry_run: bool,
        owner: &str,
        repository: &str,
        changelog_last_changes: Option<String>,
        branch: &str,
    ) -> Result<(), anyhow::Error> {
        self.ui
            .write_str_ln("creating and checking out release branch");
        self.git_client.checkout_branch()?;
        std::fs::write(changelog_placement, changelog.as_bytes())?;
        self.ui.write_str_ln("committed changelog files");
        self.git_client
            .commit_and_push(next_version.to_string(), dry_run)?;
        let _pr_number = match self.gitea_client.get_pull_request(owner, repository)? {
            Some(existing_pr) => {
                self.ui.write_str_ln("found existing pull request");
                self.ui.write_str_ln("updating pull request");
                if !dry_run {
                    self.gitea_client.update_pull_request(
                        owner,
                        repository,
                        &next_version.to_string(),
                        &changelog_last_changes
                            .ok_or(anyhow::anyhow!("could not get the latest changes"))?,
                        existing_pr,
                    )?
                } else {
                    tracing::debug!("updating pull request (dry_run)");
                    1
                }
            }
            None => {
                self.ui.write_str_ln("creating pull request");
                if !dry_run {
                    self.gitea_client.create_pull_request(
                        owner,
                        repository,
                        &next_version.to_string(),
                        &changelog_last_changes
                            .ok_or(anyhow::anyhow!("could not get the latest changes"))?,
                        branch,
                    )?
                } else {
                    tracing::debug!("creating pull request (dry_run)");
                    1
                }
            }
        };
        Ok(())
    }

    fn fetch_commits_since_last_tag(
        &self,
        owner: &str,
        repository: &str,
        significant_tag: &Option<Tag>,
        branch: &str,
    ) -> Result<Vec<Commit>, anyhow::Error> {
        let commits = self.gitea_client.get_commits_since(
            owner,
            repository,
            significant_tag.as_ref().map(|st| st.commit.sha.as_str()),
            branch,
        )?;
        Ok(commits)
    }

    fn get_most_significant_tag(
        &self,
        owner: &str,
        repository: &str,
    ) -> Result<Option<Tag>, anyhow::Error> {
        let tags = self.gitea_client.get_tags(owner, repository)?;
        let significant_tag = get_most_significant_version(tags.iter().collect());
        Ok(significant_tag.cloned())
    }

    fn check_git_remote_connection(
        &self,
        owner: &str,
        repository: &str,
    ) -> Result<(), anyhow::Error> {
        self.gitea_client
            .connect(owner, repository)
            .context("failed to connect to gitea repository")?;
        Ok(())
    }
}

fn compose_changelog(
    commit_strs: &Vec<String>,
    next_version: &Version,
    source: &std::path::PathBuf,
) -> Result<(std::path::PathBuf, String, Option<String>), anyhow::Error> {
    let builder = ChangeLogBuilder::new(commit_strs, next_version.to_string()).build();
    let changelog_placement = source.join("CHANGELOG.md");
    let changelog = match std::fs::read_to_string(&changelog_placement).ok() {
        Some(existing_changelog) => builder.prepend(existing_changelog)?,
        None => builder.generate()?,
    };
    let changelog_last_changes = changelog_parser::last_changes(&changelog)?;
    Ok((changelog_placement, changelog, changelog_last_changes))
}

fn parse_conventional_commits(
    current_version: Version,
    commits: Vec<Commit>,
) -> anyhow::Result<Option<(Vec<String>, Version)>> {
    let commit_strs = commits
        .iter()
        .map(|c| c.commit.message.clone())
        .collect::<Vec<_>>();

    if commit_strs.is_empty() {
        tracing::info!("no commits to base release on");
        return Ok(None);
    }

    let next_version = current_version.next(&commit_strs);

    Ok(Some((commit_strs, next_version)))
}

fn get_current_version(significant_tag: Option<Tag>) -> Version {
    significant_tag
        .map(|st| Version::try_from(st).unwrap())
        .unwrap_or(Version::new(0, 0, 0))
}