use anyhow::Context;
use reqwest::header::{HeaderMap, HeaderValue};
use semver::Version;
use serde::{Deserialize, Serialize};

pub trait RemoteGitEngine {
    fn connect(&self, owner: &str, repo: &str) -> anyhow::Result<()>;

    fn get_tags(&self, owner: &str, repo: &str) -> anyhow::Result<Vec<Tag>>;

    fn get_commits_since(
        &self,
        owner: &str,
        repo: &str,
        since_sha: Option<&str>,
        branch: &str,
    ) -> anyhow::Result<Vec<Commit>>;

    fn get_pull_request(&self, owner: &str, repo: &str) -> anyhow::Result<Option<usize>>;

    fn create_pull_request(
        &self,
        owner: &str,
        repo: &str,
        version: &str,
        body: &str,
        base: &str,
    ) -> anyhow::Result<usize>;

    fn update_pull_request(
        &self,
        owner: &str,
        repo: &str,
        version: &str,
        body: &str,
        index: usize,
    ) -> anyhow::Result<usize>;

    fn create_release(
        &self,
        owner: &str,
        repo: &str,
        version: &str,
        body: &str,
        prerelease: bool,
    ) -> anyhow::Result<Release>;
}

pub type DynRemoteGitClient = Box<dyn RemoteGitEngine>;

#[allow(dead_code)]
pub struct GiteaClient {
    url: String,
    token: Option<String>,
    pub allow_insecure: bool,
}

const APP_USER_AGENT: &str = concat!(env!("CARGO_PKG_NAME"), "/", env!("CARGO_PKG_VERSION"),);

impl GiteaClient {
    pub fn new(url: &str, token: Option<&str>) -> Self {
        Self {
            url: url.into(),
            token: token.map(|t| t.into()),
            allow_insecure: false,
        }
    }

    fn create_client(&self) -> anyhow::Result<reqwest::blocking::Client> {
        let cb = reqwest::blocking::ClientBuilder::new();
        let mut header_map = HeaderMap::new();
        if let Some(token) = &self.token {
            header_map.insert(
                "Authorization",
                HeaderValue::from_str(format!("token {}", token).as_str())?,
            );
        }

        let client = cb
            .user_agent(APP_USER_AGENT)
            .default_headers(header_map)
            .danger_accept_invalid_certs(self.allow_insecure)
            .build()?;

        Ok(client)
    }

    fn get_commits_since_inner<F>(
        &self,
        owner: &str,
        repo: &str,
        since_sha: Option<&str>,
        branch: &str,
        get_commits: F,
    ) -> anyhow::Result<Vec<Commit>>
    where
        F: Fn(&str, &str, &str, usize) -> anyhow::Result<(Vec<Commit>, bool)>,
    {
        let mut commits = Vec::new();
        let mut page = 1;

        let owner: String = owner.into();
        let repo: String = repo.into();
        let since_sha: Option<String> = since_sha.map(|ss| ss.into());
        let branch: String = branch.into();
        let mut found_commit = false;
        loop {
            let (new_commits, has_more) = get_commits(&owner, &repo, &branch, page)?;

            for commit in new_commits {
                if let Some(since_sha) = &since_sha {
                    if commit.sha.contains(since_sha) {
                        found_commit = true;
                    } else if !found_commit {
                        commits.push(commit);
                    }
                } else {
                    commits.push(commit);
                }
            }

            if !has_more {
                break;
            }
            page += 1;
        }

        if !found_commit && since_sha.is_some() {
            return Err(anyhow::anyhow!(
                "sha was not found in commit chain: {} on branch: {}",
                since_sha.unwrap_or("".into()),
                branch
            ));
        }

        Ok(commits)
    }

    fn get_pull_request_inner<F>(
        &self,
        owner: &str,
        repo: &str,
        request_pull_request: F,
    ) -> anyhow::Result<Option<usize>>
    where
        F: Fn(&str, &str, usize) -> anyhow::Result<(Vec<PullRequest>, bool)>,
    {
        let mut page = 1;

        let owner: String = owner.into();
        let repo: String = repo.into();
        loop {
            let (pull_requests, has_more) = request_pull_request(&owner, &repo, page)?;

            for pull_request in pull_requests {
                if pull_request.head.r#ref.contains("cuddle-please/release") {
                    return Ok(Some(pull_request.number));
                }
            }

            if !has_more {
                break;
            }
            page += 1;
        }

        Ok(None)
    }
}

impl RemoteGitEngine for GiteaClient {
    fn connect(&self, owner: &str, repo: &str) -> anyhow::Result<()> {
        let client = self.create_client()?;

        tracing::trace!(owner = &owner, repo = &repo, "gitea connect");

        let request = client
            .get(format!(
                "{}/api/v1/repos/{}/{}",
                &self.url.trim_end_matches('/'),
                owner,
                repo
            ))
            .build()?;

        let resp = client.execute(request)?;

        if !resp.status().is_success() {
            resp.error_for_status()?;
            return Ok(());
        }

        Ok(())
    }

    fn get_tags(&self, owner: &str, repo: &str) -> anyhow::Result<Vec<Tag>> {
        let client = self.create_client()?;

        let request = client
            .get(format!(
                "{}/api/v1/repos/{}/{}/tags",
                &self.url.trim_end_matches('/'),
                owner,
                repo
            ))
            .build()?;

        let resp = client.execute(request)?;

        if !resp.status().is_success() {
            return Err(anyhow::anyhow!(resp.error_for_status().unwrap_err()));
        }
        let tags: Vec<Tag> = resp.json()?;

        Ok(tags)
    }

    fn get_commits_since(
        &self,
        owner: &str,
        repo: &str,
        since_sha: Option<&str>,
        branch: &str,
    ) -> anyhow::Result<Vec<Commit>> {
        let get_commits_since_page = |owner: &str,
                                      repo: &str,
                                      branch: &str,
                                      page: usize|
         -> anyhow::Result<(Vec<Commit>, bool)> {
            let client = self.create_client()?;
            tracing::trace!(
                owner = owner,
                repo = repo,
                branch = branch,
                page = page,
                "fetching tags"
            );
            let request = client
                .get(format!(
                    "{}/api/v1/repos/{}/{}/commits?page={}&limit={}&sha={}&stat=false&verification=false&files=false",
                    &self.url.trim_end_matches('/'),
                    owner,
                    repo,
                    page,
                    50,
                    branch,
                ))
                .build()?;
            let resp = client.execute(request)?;

            let mut has_more = false;

            if let Some(gitea_has_more) = resp.headers().get("X-HasMore") {
                let gitea_has_more = gitea_has_more.to_str()?;
                if gitea_has_more == "true" || gitea_has_more == "True" {
                    has_more = true;
                }
            }

            if !resp.status().is_success() {
                return Err(anyhow::anyhow!(resp.error_for_status().unwrap_err()));
            }
            let commits: Vec<Commit> = resp.json()?;

            Ok((commits, has_more))
        };

        let commits =
            self.get_commits_since_inner(owner, repo, since_sha, branch, get_commits_since_page)?;

        Ok(commits)
    }

    fn get_pull_request(&self, owner: &str, repo: &str) -> anyhow::Result<Option<usize>> {
        let request_pull_request =
            |owner: &str, repo: &str, page: usize| -> anyhow::Result<(Vec<PullRequest>, bool)> {
                let client = self.create_client()?;
                tracing::trace!(owner = owner, repo = repo, "fetching pull-requests");
                let request = client
                    .get(format!(
                        "{}/api/v1/repos/{}/{}/pulls?state=open&sort=recentupdate&page={}&limit={}",
                        &self.url.trim_end_matches('/'),
                        owner,
                        repo,
                        page,
                        50,
                    ))
                    .build()?;
                let resp = client.execute(request)?;

                let mut has_more = false;

                if let Some(gitea_has_more) = resp.headers().get("X-HasMore") {
                    let gitea_has_more = gitea_has_more.to_str()?;
                    if gitea_has_more == "true" || gitea_has_more == "True" {
                        has_more = true;
                    }
                }

                if !resp.status().is_success() {
                    return Err(anyhow::anyhow!(resp.error_for_status().unwrap_err()));
                }
                let commits: Vec<PullRequest> = resp.json()?;

                Ok((commits, has_more))
            };

        self.get_pull_request_inner(owner, repo, request_pull_request)
    }

    fn create_pull_request(
        &self,
        owner: &str,
        repo: &str,
        version: &str,
        body: &str,
        base: &str,
    ) -> anyhow::Result<usize> {
        #[derive(Clone, Debug, Serialize, Deserialize)]
        struct CreatePullRequestOption {
            base: String,
            body: String,
            head: String,
            title: String,
        }

        let client = self.create_client()?;

        let request = CreatePullRequestOption {
            base: base.into(),
            body: body.into(),
            head: "cuddle-please/release".into(),
            title: format!("chore(release): v{}", version),
        };

        tracing::trace!(
            owner = owner,
            repo = repo,
            version = version,
            base = base,
            "create pull_request"
        );
        let request = client
            .post(format!(
                "{}/api/v1/repos/{}/{}/pulls",
                &self.url.trim_end_matches('/'),
                owner,
                repo,
            ))
            .json(&request)
            .build()?;
        let resp = client.execute(request)?;

        if !resp.status().is_success() {
            return Err(anyhow::anyhow!(resp.error_for_status().unwrap_err()));
        }
        let commits: PullRequest = resp.json()?;

        Ok(commits.number)
    }

    fn update_pull_request(
        &self,
        owner: &str,
        repo: &str,
        version: &str,
        body: &str,
        index: usize,
    ) -> anyhow::Result<usize> {
        #[derive(Clone, Debug, Serialize, Deserialize)]
        struct CreatePullRequestOption {
            body: String,
            title: String,
        }

        let client = self.create_client()?;

        let request = CreatePullRequestOption {
            body: body.into(),
            title: format!("chore(release): v{}", version),
        };

        tracing::trace!(
            owner = owner,
            repo = repo,
            version = version,
            "update pull_request"
        );
        let request = client
            .patch(format!(
                "{}/api/v1/repos/{}/{}/pulls/{}",
                &self.url.trim_end_matches('/'),
                owner,
                repo,
                index
            ))
            .json(&request)
            .build()?;
        let resp = client.execute(request)?;

        if !resp.status().is_success() {
            return Err(anyhow::anyhow!(resp.error_for_status().unwrap_err()));
        }
        let commits: PullRequest = resp.json()?;

        Ok(commits.number)
    }

    fn create_release(
        &self,
        owner: &str,
        repo: &str,
        version: &str,
        body: &str,
        prerelease: bool,
    ) -> anyhow::Result<Release> {
        #[derive(Clone, Debug, Serialize, Deserialize)]
        struct CreateReleaseOption {
            body: String,
            draft: bool,
            name: String,
            prerelease: bool,
            #[serde(alias = "tag_name")]
            tag_name: String,
        }

        let client = self.create_client()?;

        let request = CreateReleaseOption {
            body: body.into(),
            draft: false,
            name: format!("v{version}"),
            prerelease,
            tag_name: format!("v{version}"),
        };

        tracing::trace!(
            owner = owner,
            repo = repo,
            version = version,
            "create release"
        );
        let request = client
            .post(format!(
                "{}/api/v1/repos/{}/{}/releases",
                &self.url.trim_end_matches('/'),
                owner,
                repo,
            ))
            .json(&request)
            .build()?;
        let resp = client.execute(request)?;

        if !resp.status().is_success() {
            return Err(anyhow::anyhow!(resp.error_for_status().unwrap_err()));
        }
        let release: Release = resp.json()?;

        Ok(release)
    }
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct Release {
    id: usize,
    url: String,
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct PullRequest {
    number: usize,
    head: PRBranchInfo,
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct PRBranchInfo {
    #[serde(alias = "ref")]
    r#ref: String,
    label: String,
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct Commit {
    sha: String,
    pub created: String,
    pub commit: CommitDetails,
}

impl Commit {
    pub fn get_title(&self) -> String {
        self.commit
            .message
            .split('\n')
            .take(1)
            .collect::<Vec<&str>>()
            .join("\n")
    }
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct CommitDetails {
    pub message: String,
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct Tag {
    pub id: String,
    pub message: String,
    pub name: String,
    pub commit: TagCommit,
}

impl TryFrom<Tag> for Version {
    type Error = anyhow::Error;

    fn try_from(value: Tag) -> Result<Self, Self::Error> {
        tracing::trace!(name = &value.name, "parsing tag into version");
        value
            .name
            .trim_start_matches("v")
            .parse::<Version>()
            .context("could not get version from tag")
    }
}
impl TryFrom<&Tag> for Version {
    type Error = anyhow::Error;

    fn try_from(value: &Tag) -> Result<Self, Self::Error> {
        tracing::trace!(name = &value.name, "parsing tag into version");
        value
            .name
            .parse::<Version>()
            .context("could not get version from tag")
    }
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq)]
pub struct TagCommit {
    pub created: String,
    pub sha: String,
    pub url: String,
}

#[cfg(test)]
mod test {
    use tracing_test::traced_test;

    use crate::gitea_client::{Commit, CommitDetails};

    use super::GiteaClient;

    fn get_api_res() -> Vec<Vec<Commit>> {
        let api_results = vec![
            vec![Commit {
                sha: "first-sha".into(),
                created: "".into(),
                commit: CommitDetails {
                    message: "first-message".into(),
                },
            }],
            vec![Commit {
                sha: "second-sha".into(),
                created: "".into(),
                commit: CommitDetails {
                    message: "second-message".into(),
                },
            }],
            vec![Commit {
                sha: "third-sha".into(),
                created: "".into(),
                commit: CommitDetails {
                    message: "third-message".into(),
                },
            }],
        ];

        api_results
    }

    fn get_commits(sha: String) -> anyhow::Result<(Vec<Vec<Commit>>, Vec<Commit>)> {
        let api_res = get_api_res();
        let client = GiteaClient::new("", Some(""));

        let commits = client.get_commits_since_inner(
            "owner",
            "repo",
            Some(&sha),
            "some-branch",
            |_, _, _, page| -> anyhow::Result<(Vec<Commit>, bool)> {
                let commit_page = api_res.get(page - 1).unwrap();

                Ok((commit_page.clone(), page != 3))
            },
        )?;

        Ok((api_res, commits))
    }

    #[test]
    #[traced_test]
    fn finds_tag_in_list() {
        let (expected, actual) = get_commits("second-sha".into()).unwrap();

        assert_eq!(
            expected.get(0).unwrap().clone().as_slice(),
            actual.as_slice()
        );
    }

    #[test]
    #[traced_test]
    fn finds_tag_in_list_already_newest_commit() {
        let (_, actual) = get_commits("first-sha".into()).unwrap();

        assert_eq!(0, actual.len());
    }

    #[test]
    #[traced_test]
    fn finds_tag_in_list_is_base() {
        let (expected, actual) = get_commits("third-sha".into()).unwrap();

        assert_eq!(expected[0..=1].concat().as_slice(), actual.as_slice());
    }

    #[test]
    #[traced_test]
    fn finds_didnt_find_tag_in_list() {
        let error = get_commits("not-found-sha".into()).unwrap_err();

        assert_eq!(
            "sha was not found in commit chain: not-found-sha on branch: some-branch",
            error.to_string()
        );
    }
}