use std::collections::HashSet;

use db::{database::AppDatabase, sqlx};
use model::repos::RepoRefModel;
use uuid::Uuid;

use crate::{bare::GitBare, errors::GitError};
#[derive(Debug, Clone)]
pub struct BranchTip {
    pub name: String,
    pub shorthand: String,
    pub target_oid: String,
}
pub fn collect_branch_tips(bare: &GitBare) -> Result<Vec<BranchTip>, GitError> {
    let repo = bare.gix_repo()?;
    let refs = repo.references().map_err(|e| {
        GitError::Internal(format!("failed to open references: {}", e))
    })?;
    let iter = refs.all().map_err(|e| {
        GitError::Internal(format!("failed to iterate refs: {}", e))
    })?;

    let mut branches = Vec::new();
    for ref_result in iter {
        let reference = ref_result.map_err(|e| {
            GitError::Internal(format!("ref iteration error: {}", e))
        })?;
        let full_name = reference.name().as_bstr().to_string();
        if !full_name.starts_with("refs/heads/") {
            continue;
        }
        let target_oid = reference
            .target()
            .try_id()
            .map(|id| id.to_hex().to_string())
            .ok_or_else(|| {
                GitError::Internal("ref has no direct target".to_string())
            })?;
        let shorthand = reference.name().shorten().to_string();
        branches.push(BranchTip {
            name: full_name,
            shorthand,
            target_oid,
        });
    }
    Ok(branches)
}
#[tracing::instrument(skip(db, bare), fields(repo_id = %repo_id))]
pub async fn sync_refs(
    db: &AppDatabase,
    bare: &GitBare,
    repo_id: Uuid,
) -> Result<(), GitError> {
    let now = chrono::Utc::now();
    let pool = db.writer();

    let existing: Vec<RepoRefModel> = sqlx::query_as::<_, RepoRefModel>(
        "SELECT id, repo, name, kind, target_sha, is_default, is_protected, created_at, updated_at FROM repo_ref WHERE repo = $1 AND kind = 'branch'"
    )
        .bind(repo_id)
        .fetch_all(pool)
        .await
        .map_err(|e| GitError::Internal(format!("failed to query branches: {}", e)))?;

    let mut existing_names: HashSet<String> =
        existing.iter().map(|r| r.name.clone()).collect();

    let branches = collect_branch_tips(bare)?;

    const PREFERRED_BRANCHES: &[&str] = &["main", "master", "trunk"];

    let current_default: Option<String> = sqlx::query_scalar::<_, String>(
        "SELECT default_branch FROM repo WHERE id = $1",
    )
    .bind(repo_id)
    .fetch_optional(pool)
    .await
    .map_err(|e| GitError::Internal(format!("failed to re-read repo: {}", e)))?
    .filter(|b| !b.is_empty());

    let mut auto_detected_branch: Option<String> = None;
    if current_default.is_none() {
        for preferred in PREFERRED_BRANCHES {
            if branches.iter().any(|b| b.shorthand == *preferred) {
                auto_detected_branch = Some((*preferred).to_string());
                break;
            }
        }
        if auto_detected_branch.is_none() {
            if let Some(first) = branches.first() {
                auto_detected_branch = Some(first.shorthand.clone());
            }
        }
    }

    for branch in &branches {
        if existing_names.contains(&branch.name) {
            existing_names.remove(&branch.name);
            sqlx::query(
                "UPDATE repo_ref SET target_sha = $1, updated_at = $2 WHERE repo = $3 AND name = $4 AND kind = 'branch'"
            )
                .bind(&branch.target_oid)
                .bind(now)
                .bind(repo_id)
                .bind(&branch.name)
                .execute(pool)
                .await
                .map_err(|e| GitError::Internal(format!("failed to update branch: {}", e)))?;
        } else {
            let new_id = Uuid::new_v4();
            sqlx::query(
                "INSERT INTO repo_ref (id, repo, name, kind, target_sha, is_default, is_protected, created_at, updated_at) VALUES ($1, $2, $3, 'branch', $4, $5, false, $6, $7)"
            )
                .bind(new_id)
                .bind(repo_id)
                .bind(&branch.name)
                .bind(&branch.target_oid)
                .bind(false)
                .bind(now)
                .bind(now)
                .execute(pool)
                .await
                .map_err(|e| GitError::Internal(format!("failed to insert branch: {}", e)))?;
        }
    }

    if !existing_names.is_empty() {
        let names_vec: Vec<String> = existing_names.into_iter().collect();
        sqlx::query("DELETE FROM repo_ref WHERE repo = $1 AND name = ANY($2) AND kind = 'branch'")
            .bind(repo_id)
            .bind(&names_vec)
            .execute(pool)
            .await
            .map_err(|e| GitError::Internal(format!("failed to delete stale branches: {}", e)))?;
    }

    if let Some(ref branch_name) = auto_detected_branch {
        let result = sqlx::query(
            "UPDATE repo SET default_branch = $1, updated_at = $2 WHERE id = $3 AND default_branch = ''"
        )
            .bind(branch_name.clone())
            .bind(now)
            .bind(repo_id)
            .execute(pool)
            .await
            .map_err(|e| GitError::Internal(format!("failed to set default branch: {}", e)))?;

        if result.rows_affected() > 0 {
            sqlx::query(
                "UPDATE repo_ref SET is_default = false, updated_at = $1 WHERE repo = $2 AND kind = 'branch'"
            )
                .bind(now)
                .bind(repo_id)
                .execute(pool)
                .await
                .map_err(|e| GitError::Internal(format!("failed to clear head flags: {}", e)))?;

            sqlx::query(
                "UPDATE repo_ref SET is_default = true, updated_at = $1 WHERE repo = $2 AND name = $3 AND kind = 'branch'"
            )
                .bind(now)
                .bind(repo_id)
                .bind(branch_name)
                .execute(pool)
                .await
                .map_err(|e| GitError::Internal(format!("failed to set head flag: {}", e)))?;
        }
    }

    Ok(())
}