use anyhow::Result;
use serde_json::{Map, Value};
use sqlx::PgPool;
use uuid::Uuid;

use crate::crypto;
use crate::db;
use crate::error::{AppError, DbErrorContext};
use crate::models::{EntryRow, EntryWriteRow};
use crate::service::add::{
    collect_field_paths, collect_key_paths, flatten_json_fields, insert_path, parse_key_path,
    parse_kv, remove_path,
};

#[derive(Debug, serde::Serialize)]
pub struct UpdateResult {
    pub name: String,
    pub folder: String,
    #[serde(rename = "type")]
    pub entry_type: String,
    pub add_tags: Vec<String>,
    pub remove_tags: Vec<String>,
    pub meta_keys: Vec<String>,
    pub remove_meta: Vec<String>,
    pub secret_keys: Vec<String>,
    pub remove_secrets: Vec<String>,
    pub linked_secrets: Vec<String>,
    pub unlinked_secrets: Vec<String>,
}

pub struct UpdateParams<'a> {
    pub name: &'a str,
    /// Optional folder for disambiguation when multiple entries share the same name.
    pub folder: Option<&'a str>,
    pub notes: Option<&'a str>,
    pub add_tags: &'a [String],
    pub remove_tags: &'a [String],
    pub meta_entries: &'a [String],
    pub remove_meta: &'a [String],
    pub secret_entries: &'a [String],
    pub secret_types: &'a std::collections::HashMap<String, String>,
    pub remove_secrets: &'a [String],
    pub link_secret_names: &'a [String],
    pub unlink_secret_names: &'a [String],
    pub user_id: Option<Uuid>,
}

pub async fn run(
    pool: &PgPool,
    params: UpdateParams<'_>,
    master_key: &[u8; 32],
) -> Result<UpdateResult> {
    let mut tx = pool.begin().await?;

    // Fetch matching rows with FOR UPDATE; use folder when provided to resolve ambiguity.
    let rows: Vec<EntryRow> = if let Some(uid) = params.user_id {
        if let Some(folder) = params.folder {
            sqlx::query_as(
                "SELECT id, version, folder, type, tags, metadata, notes FROM entries \
                 WHERE user_id = $1 AND folder = $2 AND name = $3 FOR UPDATE",
            )
            .bind(uid)
            .bind(folder)
            .bind(params.name)
            .fetch_all(&mut *tx)
            .await?
        } else {
            sqlx::query_as(
                "SELECT id, version, folder, type, tags, metadata, notes FROM entries \
                 WHERE user_id = $1 AND name = $2 FOR UPDATE",
            )
            .bind(uid)
            .bind(params.name)
            .fetch_all(&mut *tx)
            .await?
        }
    } else if let Some(folder) = params.folder {
        sqlx::query_as(
            "SELECT id, version, folder, type, tags, metadata, notes FROM entries \
             WHERE user_id IS NULL AND folder = $1 AND name = $2 FOR UPDATE",
        )
        .bind(folder)
        .bind(params.name)
        .fetch_all(&mut *tx)
        .await?
    } else {
        sqlx::query_as(
            "SELECT id, version, folder, type, tags, metadata, notes FROM entries \
             WHERE user_id IS NULL AND name = $1 FOR UPDATE",
        )
        .bind(params.name)
        .fetch_all(&mut *tx)
        .await?
    };

    let row = match rows.len() {
        0 => {
            tx.rollback().await?;
            return Err(AppError::NotFoundEntry.into());
        }
        1 => rows.into_iter().next().unwrap(),
        _ => {
            tx.rollback().await?;
            let folders: Vec<&str> = rows.iter().map(|r| r.folder.as_str()).collect();
            anyhow::bail!(
                "Ambiguous: {} entries named '{}' found in folders: [{}]. \
                 Specify 'folder' to disambiguate.",
                rows.len(),
                params.name,
                folders.join(", ")
            )
        }
    };

    if let Err(e) = db::snapshot_entry_history(
        &mut tx,
        db::EntrySnapshotParams {
            entry_id: row.id,
            user_id: params.user_id,
            folder: &row.folder,
            entry_type: &row.entry_type,
            name: params.name,
            version: row.version,
            action: "update",
            tags: &row.tags,
            metadata: &row.metadata,
        },
    )
    .await
    {
        tracing::warn!(error = %e, "failed to snapshot entry history before update");
    }

    let mut tags: Vec<String> = row.tags.clone();
    for t in params.add_tags {
        if !tags.contains(t) {
            tags.push(t.clone());
        }
    }
    tags.retain(|t| !params.remove_tags.contains(t));

    let mut meta_map: Map<String, Value> = match row.metadata.clone() {
        Value::Object(m) => m,
        _ => Map::new(),
    };
    for entry in params.meta_entries {
        let (path, value) = parse_kv(entry)?;
        insert_path(&mut meta_map, &path, value)?;
    }
    for key in params.remove_meta {
        let path = parse_key_path(key)?;
        remove_path(&mut meta_map, &path)?;
    }
    let metadata = Value::Object(meta_map);

    let new_notes = params.notes.unwrap_or(&row.notes);

    let result = sqlx::query(
        "UPDATE entries SET tags = $1, metadata = $2, notes = $3, \
         version = version + 1, updated_at = NOW() \
         WHERE id = $4 AND version = $5",
    )
    .bind(&tags)
    .bind(&metadata)
    .bind(new_notes)
    .bind(row.id)
    .bind(row.version)
    .execute(&mut *tx)
    .await?;

    if result.rows_affected() == 0 {
        tx.rollback().await?;
        return Err(AppError::ConcurrentModification.into());
    }

    for entry in params.secret_entries {
        let (path, field_value) = parse_kv(entry)?;
        let flat = flatten_json_fields("", &{
            let mut m = Map::new();
            insert_path(&mut m, &path, field_value)?;
            Value::Object(m)
        });

        for (field_name, fv) in &flat {
            let encrypted = crypto::encrypt_json(master_key, fv)?;

            #[derive(sqlx::FromRow)]
            struct ExistingField {
                id: Uuid,
                encrypted: Vec<u8>,
            }
            let ef: Option<ExistingField> = sqlx::query_as(
                "SELECT s.id, s.encrypted \
                 FROM entry_secrets es \
                 JOIN secrets s ON s.id = es.secret_id \
                 WHERE es.entry_id = $1 AND s.name = $2",
            )
            .bind(row.id)
            .bind(field_name)
            .fetch_optional(&mut *tx)
            .await?;

            if let Some(ef) = &ef
                && let Err(e) = db::snapshot_secret_history(
                    &mut tx,
                    db::SecretSnapshotParams {
                        secret_id: ef.id,
                        name: field_name,
                        encrypted: &ef.encrypted,
                        action: "update",
                    },
                )
                .await
            {
                tracing::warn!(error = %e, "failed to snapshot secret field history");
            }

            if let Some(ef) = ef {
                sqlx::query(
                    "UPDATE secrets SET encrypted = $1, version = version + 1, updated_at = NOW() WHERE id = $2",
                )
                .bind(&encrypted)
                .bind(ef.id)
                .execute(&mut *tx)
                .await?;
            } else {
                let secret_type = params
                    .secret_types
                    .get(field_name)
                    .map(|s| s.as_str())
                    .unwrap_or("text");
                let secret_id: Uuid = sqlx::query_scalar(
                    "INSERT INTO secrets (user_id, name, type, encrypted) VALUES ($1, $2, $3, $4) RETURNING id",
                )
                .bind(params.user_id)
                .bind(field_name.to_string())
                .bind(secret_type)
                .bind(&encrypted)
                .fetch_one(&mut *tx)
                .await
                .map_err(|e| AppError::from_db_error(e, DbErrorContext::secret_name(field_name)))?;
                sqlx::query("INSERT INTO entry_secrets (entry_id, secret_id) VALUES ($1, $2)")
                    .bind(row.id)
                    .bind(secret_id)
                    .execute(&mut *tx)
                    .await?;
            }
        }
    }

    for key in params.remove_secrets {
        let path = parse_key_path(key)?;
        let field_name = path.join(".");

        #[derive(sqlx::FromRow)]
        struct FieldToDelete {
            id: Uuid,
            encrypted: Vec<u8>,
        }
        let field: Option<FieldToDelete> = sqlx::query_as(
            "SELECT s.id, s.encrypted \
             FROM entry_secrets es \
             JOIN secrets s ON s.id = es.secret_id \
             WHERE es.entry_id = $1 AND s.name = $2",
        )
        .bind(row.id)
        .bind(&field_name)
        .fetch_optional(&mut *tx)
        .await?;

        if let Some(f) = field {
            if let Err(e) = db::snapshot_secret_history(
                &mut tx,
                db::SecretSnapshotParams {
                    secret_id: f.id,
                    name: &field_name,
                    encrypted: &f.encrypted,
                    action: "delete",
                },
            )
            .await
            {
                tracing::warn!(error = %e, "failed to snapshot secret field history before delete");
            }
            sqlx::query("DELETE FROM entry_secrets WHERE entry_id = $1 AND secret_id = $2")
                .bind(row.id)
                .bind(f.id)
                .execute(&mut *tx)
                .await?;
            sqlx::query(
                "DELETE FROM secrets s \
                 WHERE s.id = $1 \
                   AND NOT EXISTS (SELECT 1 FROM entry_secrets es WHERE es.secret_id = s.id)",
            )
            .bind(f.id)
            .execute(&mut *tx)
            .await?;
        }
    }

    // Link existing secrets by name
    let mut linked_secrets = Vec::new();
    for link_name in params.link_secret_names {
        let link_name = link_name.trim();
        if link_name.is_empty() {
            anyhow::bail!("link_secret_names contains an empty name");
        }
        let secret_ids: Vec<Uuid> = if let Some(uid) = params.user_id {
            sqlx::query_scalar("SELECT id FROM secrets WHERE user_id = $1 AND name = $2")
                .bind(uid)
                .bind(link_name)
                .fetch_all(&mut *tx)
                .await?
        } else {
            sqlx::query_scalar("SELECT id FROM secrets WHERE user_id IS NULL AND name = $1")
                .bind(link_name)
                .fetch_all(&mut *tx)
                .await?
        };

        match secret_ids.len() {
            0 => anyhow::bail!("Not found: secret named '{}'", link_name),
            1 => {
                sqlx::query(
                    "INSERT INTO entry_secrets (entry_id, secret_id) VALUES ($1, $2) ON CONFLICT DO NOTHING",
                )
                .bind(row.id)
                .bind(secret_ids[0])
                .execute(&mut *tx)
                .await?;
                linked_secrets.push(link_name.to_string());
            }
            n => anyhow::bail!(
                "Ambiguous: {} secrets named '{}' found. Please deduplicate names first.",
                n,
                link_name
            ),
        }
    }

    // Unlink secrets by name
    let mut unlinked_secrets = Vec::new();
    for unlink_name in params.unlink_secret_names {
        let unlink_name = unlink_name.trim();
        if unlink_name.is_empty() {
            continue;
        }

        #[derive(sqlx::FromRow)]
        struct SecretToUnlink {
            id: Uuid,
            encrypted: Vec<u8>,
        }
        let secret: Option<SecretToUnlink> = sqlx::query_as(
            "SELECT s.id, s.encrypted \
             FROM entry_secrets es \
             JOIN secrets s ON s.id = es.secret_id \
             WHERE es.entry_id = $1 AND s.name = $2",
        )
        .bind(row.id)
        .bind(unlink_name)
        .fetch_optional(&mut *tx)
        .await?;

        if let Some(s) = secret {
            if let Err(e) = db::snapshot_secret_history(
                &mut tx,
                db::SecretSnapshotParams {
                    secret_id: s.id,
                    name: unlink_name,
                    encrypted: &s.encrypted,
                    action: "delete",
                },
            )
            .await
            {
                tracing::warn!(error = %e, "failed to snapshot secret field history before unlink");
            }
            sqlx::query("DELETE FROM entry_secrets WHERE entry_id = $1 AND secret_id = $2")
                .bind(row.id)
                .bind(s.id)
                .execute(&mut *tx)
                .await?;
            sqlx::query(
                "DELETE FROM secrets s \
                 WHERE s.id = $1 \
                   AND NOT EXISTS (SELECT 1 FROM entry_secrets es WHERE es.secret_id = s.id)",
            )
            .bind(s.id)
            .execute(&mut *tx)
            .await?;
            unlinked_secrets.push(unlink_name.to_string());
        }
    }

    let meta_keys = collect_key_paths(params.meta_entries)?;
    let remove_meta_keys = collect_field_paths(params.remove_meta)?;
    let secret_keys = collect_key_paths(params.secret_entries)?;
    let remove_secret_keys = collect_field_paths(params.remove_secrets)?;

    crate::audit::log_tx(
        &mut tx,
        params.user_id,
        "update",
        &row.folder,
        &row.entry_type,
        params.name,
        serde_json::json!({
            "add_tags": params.add_tags,
            "remove_tags": params.remove_tags,
            "meta_keys": meta_keys,
            "remove_meta": remove_meta_keys,
            "secret_keys": secret_keys,
            "remove_secrets": remove_secret_keys,
            "linked_secrets": linked_secrets,
            "unlinked_secrets": unlinked_secrets,
        }),
    )
    .await;

    tx.commit().await?;

    Ok(UpdateResult {
        name: params.name.to_string(),
        folder: row.folder.clone(),
        entry_type: row.entry_type.clone(),
        add_tags: params.add_tags.to_vec(),
        remove_tags: params.remove_tags.to_vec(),
        meta_keys,
        remove_meta: remove_meta_keys,
        secret_keys,
        remove_secrets: remove_secret_keys,
        linked_secrets,
        unlinked_secrets,
    })
}

/// Update non-sensitive entry columns by primary key (multi-tenant: `user_id` must match).
/// Does not read or modify `secrets` rows.
pub struct UpdateEntryFieldsByIdParams<'a> {
    pub folder: &'a str,
    pub entry_type: &'a str,
    pub name: &'a str,
    pub notes: &'a str,
    pub tags: &'a [String],
    pub metadata: &'a serde_json::Value,
}

pub async fn update_fields_by_id(
    pool: &PgPool,
    entry_id: Uuid,
    user_id: Uuid,
    params: UpdateEntryFieldsByIdParams<'_>,
) -> Result<()> {
    if params.folder.chars().count() > 128 {
        anyhow::bail!("folder must be at most 128 characters");
    }
    if params.entry_type.chars().count() > 64 {
        anyhow::bail!("type must be at most 64 characters");
    }
    if params.name.chars().count() > 256 {
        anyhow::bail!("name must be at most 256 characters");
    }

    let mut tx = pool.begin().await?;

    let row: Option<EntryWriteRow> = sqlx::query_as(
        "SELECT id, version, folder, type, name, tags, metadata, notes FROM entries \
         WHERE id = $1 AND user_id = $2 FOR UPDATE",
    )
    .bind(entry_id)
    .bind(user_id)
    .fetch_optional(&mut *tx)
    .await?;

    let row = match row {
        Some(r) => r,
        None => {
            tx.rollback().await?;
            return Err(AppError::NotFoundEntry.into());
        }
    };

    if let Err(e) = db::snapshot_entry_history(
        &mut tx,
        db::EntrySnapshotParams {
            entry_id: row.id,
            user_id: Some(user_id),
            folder: &row.folder,
            entry_type: &row.entry_type,
            name: &row.name,
            version: row.version,
            action: "update",
            tags: &row.tags,
            metadata: &row.metadata,
        },
    )
    .await
    {
        tracing::warn!(error = %e, "failed to snapshot entry history before web update");
    }

    let entry_type = params.entry_type.trim();

    let res = sqlx::query(
        "UPDATE entries SET folder = $1, type = $2, name = $3, notes = $4, tags = $5, metadata = $6, \
         version = version + 1, updated_at = NOW() \
         WHERE id = $7 AND version = $8",
    )
    .bind(params.folder)
    .bind(entry_type)
    .bind(params.name)
    .bind(params.notes)
    .bind(params.tags)
    .bind(params.metadata)
    .bind(row.id)
    .bind(row.version)
    .execute(&mut *tx)
    .await
    .map_err(|e| {
        if let sqlx::Error::Database(ref d) = e
            && d.code().as_deref() == Some("23505")
        {
            return AppError::ConflictEntryName {
                folder: params.folder.to_string(),
                name: params.name.to_string(),
            };
        }
        AppError::Internal(e.into())
    })?;

    if res.rows_affected() == 0 {
        tx.rollback().await?;
        return Err(AppError::ConcurrentModification.into());
    }

    crate::audit::log_tx(
        &mut tx,
        Some(user_id),
        "update",
        params.folder,
        entry_type,
        params.name,
        serde_json::json!({
            "source": "web",
            "entry_id": entry_id,
            "fields": ["folder", "type", "name", "notes", "tags", "metadata"],
        }),
    )
    .await;

    tx.commit().await?;
    Ok(())
}