use std::time::Duration;

use serde::Deserialize;
use serde_json::{Value, json};

use crate::{
    bot::{ReviewItem, ReviewResult},
    errors::AppError,
};

pub struct GiteaAPI {
    base_url: String,
    client: reqwest::Client,
}

impl GiteaAPI {
    pub fn new(base_url: &str, token: &str, timeout: u64) -> anyhow::Result<Self> {
        let mut default_headers = reqwest::header::HeaderMap::new();
        default_headers.insert(
            reqwest::header::HeaderName::from_static("authorization"),
            reqwest::header::HeaderValue::from_str(&format!("Bearer {}", token))?,
        );

        Ok(Self {
            base_url: String::from(base_url),
            client: reqwest::Client::builder()
                .timeout(Duration::from_secs(timeout))
                .default_headers(default_headers)
                .build()?,
        })
    }

    pub async fn comment(
        &self,
        body: &str,
        full_name: &str,
        index: u64,
    ) -> anyhow::Result<Comment> {
        let url = format!(
            "{}/api/v1/repos/{}/issues/{}/comments",
            self.base_url, full_name, index
        );

        let res = self
            .client
            .post(url)
            .json(&json!({
                "body": body
            }))
            .send()
            .await?;

        if !res.status().is_success() {
            return Err(anyhow::anyhow!("Failed to comment: {}", res.status()));
        }

        res.json::<Comment>().await.map_err(anyhow::Error::from)
    }

    pub async fn edit_comment(
        &self,
        body: &str,
        full_name: &str,
        comment_id: u64,
    ) -> anyhow::Result<()> {
        let url = format!(
            "{}/api/v1/repos/{}/issues/comments/{}",
            self.base_url, full_name, comment_id
        );

        let res = self
            .client
            .patch(url)
            .json(&json!({
                "body": body
            }))
            .send()
            .await?;

        if !res.status().is_success() {
            return Err(anyhow::anyhow!("Failed to comment: {}", res.status()));
        }

        Ok(())
    }

    pub async fn post_pull_request_review(
        &self,
        review_result: &ReviewResult,
        full_name: &str,
        index: u64,
    ) -> anyhow::Result<()> {
        let url = format!(
            "{}/api/v1/repos/{}/pulls/{}/reviews",
            self.base_url, full_name, index
        );

        let comments = &&review_result
            .reviews
            .iter()
            .filter(|r| r.line.is_some())
            .map(|r| {
                let path = r.filename.clone();
                let line = r.line.unwrap_or(0);
                let body = r.message.clone();

                json!({
                    "path": path,
                    "new_position": line,
                    "body": body
                })
            })
            .collect::<Vec<_>>();

        let res = self
            .client
            .post(url)
            .json(&json!({
                "event": "COMMENT",
                "body": review_result.comment,
                "comments": comments
            }))
            .send()
            .await?;

        if !res.status().is_success() {
            return Err(anyhow::anyhow!("Failed to post review: {}", res.status()));
        }

        Ok(())
    }
}

#[derive(Debug)]
pub enum WebhookType {
    Review(ReviewPayload),
}

#[derive(Deserialize, Debug)]
pub struct ReviewPayload {
    pub action: String,
    pub pull_request: PullRequest,
    pub repository: Repository,
    pub comment: Comment,
}

#[derive(Deserialize, Debug)]
pub struct PullRequest {
    pub id: u64,
    pub diff_url: String,
    pub number: u64,
    pub title: String,
}

#[derive(Deserialize, Debug)]
pub struct Comment {
    pub id: u64,
    pub body: String,
    pub user: User,
}

#[derive(Deserialize, Debug)]
pub struct User {
    pub id: u64,
}

#[derive(Deserialize, Debug)]
pub struct Repository {
    pub full_name: String,
}

impl WebhookType {
    pub fn from_event(event: &str, bot_name: &str, json: Value) -> Result<Self, AppError> {
        let wb = match event {
            "pull_request_comment" => Ok(WebhookType::Review(serde_json::from_value(json)?)),
            _ => Err(AppError::UnknownEventErr),
        }?;

        let pr_body = match &wb {
            WebhookType::Review(review_payload) => &review_payload.comment.body,
        };

        if !pr_body.starts_with(&format!("@{}", bot_name)) {
            return Err(AppError::UnauthorizedUserErr);
        }

        let action = match &wb {
            WebhookType::Review(review_payload) => &review_payload.action,
        };

        if action != "created" {
            return Err(AppError::InvalidActionErr);
        }

        Ok(wb)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;

    #[test]
    fn test_from_event_valid_pull_request_comment() {
        let json = json!({
            "action": "created",
            "pull_request": {
                "id": 42,
                "diff_url": "https://mydiff.fr"
            },
            "comment": {
                "id": 7,
                "body": "@test_bot LGTM",
                "user": {
                    "id": 100
                }
            }
        });

        let result = WebhookType::from_event("pull_request_comment", "test_bot", json);
        assert!(result.is_ok());

        match result.unwrap() {
            WebhookType::Review(payload) => {
                assert_eq!(payload.action, "created");
                assert_eq!(payload.pull_request.id, 42);
                assert_eq!(payload.comment.id, 7);
                assert_eq!(payload.comment.body, "@test_bot LGTM");
                assert_eq!(payload.comment.user.id, 100);
            }
        }
    }

    #[test]
    fn test_from_event_unknown_event() {
        let json = json!({});
        let result = WebhookType::from_event("push", "test_bot", json);
        assert!(result.is_err());

        match result.unwrap_err() {
            AppError::UnknownEventErr => {}
            _ => panic!("expected UnknownEventErr"),
        }
    }

    #[test]
    fn test_from_event_malformed_json() {
        let json = json!({
            "action": "created"
            // pull_request and comment are missing
        });

        let result = WebhookType::from_event("pull_request_comment", "test_bot", json);
        assert!(result.is_err());

        match result.unwrap_err() {
            AppError::BadJsonStructErr(_) => {}
            _ => panic!("expected BadJsonStructErr"),
        }
    }

    #[test]
    fn test_from_event_rejects_non_created_action() {
        let json = json!({
            "action": "edited",
            "pull_request": {
                "id": 1,
                "diff_url": "https://mydiff.fr"
            },
            "comment": {
                "id": 1,
                "body": "@test_bot body",
                "user": {
                    "id": 1
                }
            }
        });

        let result = WebhookType::from_event("pull_request_comment", "test_bot", json);
        assert!(result.is_err());

        match result.unwrap_err() {
            AppError::InvalidActionErr => {}
            _ => panic!("expected InvalidActionErr"),
        }
    }

    #[test]
    fn test_deserialize_review_payload() {
        let json = json!({
            "action": "created",
            "pull_request": {
                "id": 99,
                "diff_url": "https://mydiff.fr"
            },
            "comment": {
                "id": 12,
                "body": "Needs work",
                "user": {
                    "id": 200
                }
            }
        });

        let payload: ReviewPayload = serde_json::from_value(json).unwrap();
        assert_eq!(payload.action, "created");
        assert_eq!(payload.pull_request.id, 99);
        assert_eq!(payload.comment.id, 12);
        assert_eq!(payload.comment.body, "Needs work");
        assert_eq!(payload.comment.user.id, 200);
    }

    #[test]
    fn test_from_event_empty_json() {
        let result = WebhookType::from_event("pull_request_comment", "test_bot", json!({}));
        assert!(result.is_err());
        assert!(matches!(result.unwrap_err(), AppError::BadJsonStructErr(_)));
    }

    #[test]
    fn test_from_event_rejects_wrong_bot_name() {
        let json = json!({
            "action": "created",
            "pull_request": {
                "id": 1,
                "diff_url": "https://mydiff.fr"
            },
            "comment": {
                "id": 1,
                "body": "@other_bot do something",
                "user": {
                    "id": 1
                }
            }
        });

        let result = WebhookType::from_event("pull_request_comment", "test_bot", json);
        assert!(matches!(result.unwrap_err(), AppError::UnauthorizedUserErr));
    }

    #[test]
    fn test_from_event_rejects_no_bot_prefix() {
        let json = json!({
            "action": "created",
            "pull_request": {
                "id": 1,
                "diff_url": "https://mydiff.fr"
            },
            "comment": {
                "id": 1,
                "body": "just a comment without bot mention",
                "user": {
                    "id": 1
                }
            }
        });

        let result = WebhookType::from_event("pull_request_comment", "test_bot", json);
        assert!(matches!(result.unwrap_err(), AppError::UnauthorizedUserErr));
    }
}