use std::fs;

use crate::core::config::{MinimalConfig, MinimalGitLabConfig, ProjectConfig};
use crate::core::db::{create_connection, run_migrations};
use crate::core::error::{LoreError, Result};
use crate::core::paths::{get_config_path, get_data_dir};
use crate::gitlab::{GitLabClient, GitLabProject};

pub struct InitInputs {
    pub gitlab_url: String,
    pub token_env_var: String,
    pub project_paths: Vec<String>,
    pub default_project: Option<String>,
}

pub struct InitOptions {
    pub config_path: Option<String>,
    pub force: bool,
    pub non_interactive: bool,
}

pub struct InitResult {
    pub config_path: String,
    pub data_dir: String,
    pub user: UserInfo,
    pub projects: Vec<ProjectInfo>,
    pub default_project: Option<String>,
}

pub struct UserInfo {
    pub username: String,
    pub name: String,
}

pub struct ProjectInfo {
    pub path: String,
    pub name: String,
}

pub async fn run_init(inputs: InitInputs, options: InitOptions) -> Result<InitResult> {
    let config_path = get_config_path(options.config_path.as_deref());
    let data_dir = get_data_dir();

    if config_path.exists() && !options.force {
        if options.non_interactive {
            return Err(LoreError::Other(format!(
                "Config file exists at {}. Use --force to overwrite.",
                config_path.display()
            )));
        }

        return Err(LoreError::Other(
            "User cancelled config overwrite.".to_string(),
        ));
    }

    if url::Url::parse(&inputs.gitlab_url).is_err() {
        return Err(LoreError::Other(format!(
            "Invalid GitLab URL: {}",
            inputs.gitlab_url
        )));
    }

    let token = std::env::var(&inputs.token_env_var).map_err(|_| LoreError::TokenNotSet {
        env_var: inputs.token_env_var.clone(),
    })?;

    let client = GitLabClient::new(&inputs.gitlab_url, &token, None);

    let gitlab_user = client.get_current_user().await.map_err(|e| {
        if matches!(e, LoreError::GitLabAuthFailed) {
            LoreError::Other(format!("Authentication failed for {}", inputs.gitlab_url))
        } else {
            e
        }
    })?;

    let user = UserInfo {
        username: gitlab_user.username,
        name: gitlab_user.name,
    };

    let mut validated_projects: Vec<(ProjectInfo, GitLabProject)> = Vec::new();

    for project_path in &inputs.project_paths {
        let project = client.get_project(project_path).await.map_err(|e| {
            if matches!(e, LoreError::GitLabNotFound { .. }) {
                LoreError::Other(format!("Project not found: {project_path}"))
            } else {
                e
            }
        })?;

        validated_projects.push((
            ProjectInfo {
                path: project_path.clone(),
                name: project.name.clone().unwrap_or_else(|| {
                    project_path
                        .split('/')
                        .next_back()
                        .unwrap_or(project_path)
                        .to_string()
                }),
            },
            project,
        ));
    }

    // Validate default_project matches one of the configured project paths
    if let Some(ref dp) = inputs.default_project {
        let matched = inputs.project_paths.iter().any(|p| {
            p.eq_ignore_ascii_case(dp)
                || p.to_ascii_lowercase()
                    .ends_with(&format!("/{}", dp.to_ascii_lowercase()))
        });
        if !matched {
            return Err(LoreError::Other(format!(
                "defaultProject '{dp}' does not match any configured project path"
            )));
        }
    }

    if let Some(parent) = config_path.parent() {
        fs::create_dir_all(parent)?;
    }

    let config = MinimalConfig {
        gitlab: MinimalGitLabConfig {
            base_url: inputs.gitlab_url,
            token_env_var: inputs.token_env_var,
        },
        projects: inputs
            .project_paths
            .iter()
            .map(|p| ProjectConfig { path: p.clone() })
            .collect(),
        default_project: inputs.default_project.clone(),
    };

    let config_json = serde_json::to_string_pretty(&config)?;
    fs::write(&config_path, format!("{config_json}\n"))?;

    fs::create_dir_all(&data_dir)?;

    let db_path = data_dir.join("lore.db");
    let conn = create_connection(&db_path)?;

    run_migrations(&conn)?;

    for (_, gitlab_project) in &validated_projects {
        conn.execute(
            "INSERT INTO projects (gitlab_project_id, path_with_namespace, default_branch, web_url)
             VALUES (?, ?, ?, ?)
             ON CONFLICT(gitlab_project_id) DO UPDATE SET
               path_with_namespace = excluded.path_with_namespace,
               default_branch = excluded.default_branch,
               web_url = excluded.web_url",
            (
                gitlab_project.id,
                &gitlab_project.path_with_namespace,
                &gitlab_project.default_branch,
                &gitlab_project.web_url,
            ),
        )?;
    }

    Ok(InitResult {
        config_path: config_path.display().to_string(),
        data_dir: data_dir.display().to_string(),
        user,
        projects: validated_projects.into_iter().map(|(p, _)| p).collect(),
        default_project: inputs.default_project,
    })
}