use std::str::FromStr;

use anyhow::{Context, Result};
use serde_json::Value;
use sqlx::PgPool;
use sqlx::postgres::{PgConnectOptions, PgPoolOptions, PgSslMode};

use crate::config::DatabaseConfig;

fn build_connect_options(config: &DatabaseConfig) -> Result<PgConnectOptions> {
    let mut options = PgConnectOptions::from_str(&config.url)
        .with_context(|| "failed to parse SECRETS_DATABASE_URL".to_string())?;

    if let Some(mode) = config.ssl_mode {
        options = options.ssl_mode(mode);
    }
    if let Some(path) = &config.ssl_root_cert {
        options = options.ssl_root_cert(path);
    }

    if config.enforce_strict_tls
        && !matches!(
            options.get_ssl_mode(),
            PgSslMode::VerifyCa | PgSslMode::VerifyFull
        )
    {
        anyhow::bail!(
            "Refusing to start in production with weak PostgreSQL TLS mode. \
             Set SECRETS_DATABASE_SSL_MODE=verify-ca or verify-full."
        );
    }

    Ok(options)
}

pub async fn create_pool(config: &DatabaseConfig) -> Result<PgPool> {
    tracing::debug!("connecting to database");
    let connect_options = build_connect_options(config)?;
    let pool = PgPoolOptions::new()
        .max_connections(10)
        .acquire_timeout(std::time::Duration::from_secs(5))
        .connect_with(connect_options)
        .await?;
    tracing::debug!("database connection established");
    Ok(pool)
}

pub async fn migrate(pool: &PgPool) -> Result<()> {
    tracing::debug!("running migrations");
    sqlx::raw_sql(
        r#"
        -- ── entries: top-level entities ─────────────────────────────────────────
        CREATE TABLE IF NOT EXISTS entries (
            id          UUID PRIMARY KEY DEFAULT uuidv7(),
            user_id     UUID,
            folder      VARCHAR(128) NOT NULL DEFAULT '',
            type        VARCHAR(64)  NOT NULL DEFAULT '',
            name        VARCHAR(256) NOT NULL,
            notes       TEXT         NOT NULL DEFAULT '',
            tags        TEXT[]       NOT NULL DEFAULT '{}',
            metadata    JSONB        NOT NULL DEFAULT '{}',
            version     BIGINT       NOT NULL DEFAULT 1,
            created_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW(),
            updated_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW()
        );

        -- Legacy unique constraint without user_id (single-user mode)
        CREATE UNIQUE INDEX IF NOT EXISTS idx_entries_unique_legacy
            ON entries(folder, name)
            WHERE user_id IS NULL;

        -- Multi-user unique constraint
        CREATE UNIQUE INDEX IF NOT EXISTS idx_entries_unique_user
            ON entries(user_id, folder, name)
            WHERE user_id IS NOT NULL;

        CREATE INDEX IF NOT EXISTS idx_entries_folder   ON entries(folder) WHERE folder <> '';
        CREATE INDEX IF NOT EXISTS idx_entries_type     ON entries(type) WHERE type <> '';
        CREATE INDEX IF NOT EXISTS idx_entries_user_id  ON entries(user_id) WHERE user_id IS NOT NULL;
        CREATE INDEX IF NOT EXISTS idx_entries_tags     ON entries USING GIN(tags);
        CREATE INDEX IF NOT EXISTS idx_entries_metadata ON entries USING GIN(metadata jsonb_path_ops);

        -- ── secrets: one row per encrypted field ─────────────────────────────────
        CREATE TABLE IF NOT EXISTS secrets (
            id          UUID PRIMARY KEY DEFAULT uuidv7(),
            user_id     UUID,
            name        VARCHAR(256) NOT NULL,
            type        VARCHAR(64)  NOT NULL DEFAULT 'text',
            encrypted   BYTEA        NOT NULL DEFAULT '\x',
            version     BIGINT       NOT NULL DEFAULT 1,
            created_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW(),
            updated_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW()
        );

        CREATE INDEX IF NOT EXISTS idx_secrets_user_id  ON secrets(user_id) WHERE user_id IS NOT NULL;
        CREATE UNIQUE INDEX IF NOT EXISTS idx_secrets_unique_user_name
            ON secrets(user_id, name) WHERE user_id IS NOT NULL;
        CREATE INDEX IF NOT EXISTS idx_secrets_name     ON secrets(name);
        CREATE INDEX IF NOT EXISTS idx_secrets_type     ON secrets(type);

        -- ── entry_secrets: N:N relation ────────────────────────────────────────────
        CREATE TABLE IF NOT EXISTS entry_secrets (
            entry_id    UUID NOT NULL REFERENCES entries(id) ON DELETE CASCADE,
            secret_id   UUID NOT NULL REFERENCES secrets(id) ON DELETE CASCADE,
            sort_order  INT NOT NULL DEFAULT 0,
            created_at  TIMESTAMPTZ NOT NULL DEFAULT NOW(),
            PRIMARY KEY(entry_id, secret_id)
        );
        CREATE INDEX IF NOT EXISTS idx_entry_secrets_secret_id ON entry_secrets(secret_id);

        -- ── audit_log: append-only operation log ─────────────────────────────────
        CREATE TABLE IF NOT EXISTS audit_log (
            id          BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
            user_id     UUID,
            action      VARCHAR(32)  NOT NULL,
            folder      VARCHAR(128) NOT NULL DEFAULT '',
            type        VARCHAR(64)  NOT NULL DEFAULT '',
            name        VARCHAR(256) NOT NULL,
            detail      JSONB        NOT NULL DEFAULT '{}',
            created_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW()
        );

        CREATE INDEX IF NOT EXISTS idx_audit_log_created      ON audit_log(created_at DESC);
        CREATE INDEX IF NOT EXISTS idx_audit_log_folder_type  ON audit_log(folder, type);
        CREATE INDEX IF NOT EXISTS idx_audit_log_user_id      ON audit_log(user_id) WHERE user_id IS NOT NULL;

        -- ── entries_history ───────────────────────────────────────────────────────
        CREATE TABLE IF NOT EXISTS entries_history (
            id          BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
            entry_id    UUID         NOT NULL,
            folder      VARCHAR(128) NOT NULL DEFAULT '',
            type        VARCHAR(64)  NOT NULL DEFAULT '',
            name        VARCHAR(256) NOT NULL,
            version     BIGINT       NOT NULL,
            action      VARCHAR(16)  NOT NULL,
            tags        TEXT[]       NOT NULL DEFAULT '{}',
            metadata    JSONB        NOT NULL DEFAULT '{}',
            created_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW()
        );

        CREATE INDEX IF NOT EXISTS idx_entries_history_entry_id
            ON entries_history(entry_id, version DESC);
        CREATE INDEX IF NOT EXISTS idx_entries_history_folder_type_name
            ON entries_history(folder, type, name, version DESC);

        -- Backfill: add user_id to entries_history for multi-tenant isolation
        ALTER TABLE entries_history ADD COLUMN IF NOT EXISTS user_id UUID;
        CREATE INDEX IF NOT EXISTS idx_entries_history_user_id
            ON entries_history(user_id) WHERE user_id IS NOT NULL;
        ALTER TABLE entries_history DROP COLUMN IF EXISTS actor;

        -- Backfill: add notes to entries if not present (fresh installs already have it)
        ALTER TABLE entries ADD COLUMN IF NOT EXISTS notes TEXT NOT NULL DEFAULT '';

        -- ── secrets_history: field-level snapshot ────────────────────────────────
        CREATE TABLE IF NOT EXISTS secrets_history (
            id              BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
            secret_id       UUID         NOT NULL,
            name            VARCHAR(256) NOT NULL,
            encrypted       BYTEA        NOT NULL DEFAULT '\x',
            action          VARCHAR(16)  NOT NULL,
            created_at      TIMESTAMPTZ  NOT NULL DEFAULT NOW()
        );

        CREATE INDEX IF NOT EXISTS idx_secrets_history_secret_id
            ON secrets_history(secret_id);

        -- Drop redundant actor column (derivable via entries_history JOIN)
        ALTER TABLE secrets_history DROP COLUMN IF EXISTS actor;

        -- ── users ─────────────────────────────────────────────────────────────────
        CREATE TABLE IF NOT EXISTS users (
            id          UUID PRIMARY KEY DEFAULT uuidv7(),
            email       VARCHAR(256),
            name        VARCHAR(256) NOT NULL DEFAULT '',
            avatar_url  TEXT,
            key_salt    BYTEA,
            key_check   BYTEA,
            key_params  JSONB,
            api_key     TEXT UNIQUE,
            created_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW(),
            updated_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW()
        );

        -- ── oauth_accounts: per-provider identity links ───────────────────────────
        CREATE TABLE IF NOT EXISTS oauth_accounts (
            id          UUID PRIMARY KEY DEFAULT uuidv7(),
            user_id     UUID         NOT NULL REFERENCES users(id) ON DELETE CASCADE,
            provider    VARCHAR(32)  NOT NULL,
            provider_id VARCHAR(256) NOT NULL,
            email       VARCHAR(256),
            name        VARCHAR(256),
            avatar_url  TEXT,
            created_at  TIMESTAMPTZ  NOT NULL DEFAULT NOW(),
            UNIQUE(provider, provider_id)
        );

        CREATE INDEX IF NOT EXISTS idx_oauth_accounts_user ON oauth_accounts(user_id);
        CREATE UNIQUE INDEX IF NOT EXISTS idx_oauth_accounts_user_provider
            ON oauth_accounts(user_id, provider);

        -- FK: user_id columns -> users(id) (nullable = legacy rows; ON DELETE SET NULL)
        DO $$ BEGIN
            IF NOT EXISTS (
                SELECT 1 FROM pg_constraint WHERE conname = 'fk_entries_user_id'
            ) THEN
                ALTER TABLE entries
                    ADD CONSTRAINT fk_entries_user_id
                    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;
            END IF;
        END $$;

        DO $$ BEGIN
            IF NOT EXISTS (
                SELECT 1 FROM pg_constraint WHERE conname = 'fk_entries_history_user_id'
            ) THEN
                ALTER TABLE entries_history
                    ADD CONSTRAINT fk_entries_history_user_id
                    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;
            END IF;
        END $$;

        DO $$ BEGIN
            IF NOT EXISTS (
                SELECT 1 FROM pg_constraint WHERE conname = 'fk_secrets_user_id'
            ) THEN
                ALTER TABLE secrets
                    ADD CONSTRAINT fk_secrets_user_id
                    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;
            END IF;
        END $$;

        DO $$ BEGIN
            IF NOT EXISTS (
                SELECT 1 FROM pg_constraint WHERE conname = 'fk_audit_log_user_id'
            ) THEN
                ALTER TABLE audit_log
                    ADD CONSTRAINT fk_audit_log_user_id
                    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;
            END IF;
        END $$;
        "#,
    )
    .execute(pool)
    .await?;
    migrate_schema(pool).await?;
    restore_plaintext_api_keys(pool).await?;

    tracing::debug!("migrations complete");
    Ok(())
}

/// Idempotent schema migration: rename namespace→folder, kind→type in existing databases.
async fn migrate_schema(pool: &PgPool) -> Result<()> {
    sqlx::raw_sql(
        r#"
        -- ── entries: rename namespace→folder, kind→type ──────────────────────────
        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'entries' AND column_name = 'namespace'
            ) THEN
                ALTER TABLE entries RENAME COLUMN namespace TO folder;
            END IF;
        END $$;

        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'entries' AND column_name = 'kind'
            ) THEN
                ALTER TABLE entries RENAME COLUMN kind TO type;
            END IF;
        END $$;

        -- ── audit_log: rename namespace→folder, kind→type ────────────────────────
        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'audit_log' AND column_name = 'namespace'
            ) THEN
                ALTER TABLE audit_log RENAME COLUMN namespace TO folder;
            END IF;
        END $$;

        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'audit_log' AND column_name = 'kind'
            ) THEN
                ALTER TABLE audit_log RENAME COLUMN kind TO type;
            END IF;
        END $$;

        -- ── entries_history: rename namespace→folder, kind→type ──────────────────
        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'entries_history' AND column_name = 'namespace'
            ) THEN
                ALTER TABLE entries_history RENAME COLUMN namespace TO folder;
            END IF;
        END $$;

        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'entries_history' AND column_name = 'kind'
            ) THEN
                ALTER TABLE entries_history RENAME COLUMN kind TO type;
            END IF;
        END $$;

        -- ── Set empty defaults for new folder/type columns ────────────────────────
        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'entries' AND column_name = 'folder'
            ) THEN
                UPDATE entries SET folder = '' WHERE folder IS NULL;
                ALTER TABLE entries ALTER COLUMN folder SET NOT NULL;
                ALTER TABLE entries ALTER COLUMN folder SET DEFAULT '';
            END IF;
        END $$;

        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'entries' AND column_name = 'type'
            ) THEN
                UPDATE entries SET type = '' WHERE type IS NULL;
                ALTER TABLE entries ALTER COLUMN type SET NOT NULL;
                ALTER TABLE entries ALTER COLUMN type SET DEFAULT '';
            END IF;
        END $$;

        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'audit_log' AND column_name = 'folder'
            ) THEN
                UPDATE audit_log SET folder = '' WHERE folder IS NULL;
                ALTER TABLE audit_log ALTER COLUMN folder SET NOT NULL;
                ALTER TABLE audit_log ALTER COLUMN folder SET DEFAULT '';
            END IF;
        END $$;

        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'audit_log' AND column_name = 'type'
            ) THEN
                UPDATE audit_log SET type = '' WHERE type IS NULL;
                ALTER TABLE audit_log ALTER COLUMN type SET NOT NULL;
                ALTER TABLE audit_log ALTER COLUMN type SET DEFAULT '';
            END IF;
        END $$;

        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'entries_history' AND column_name = 'folder'
            ) THEN
                UPDATE entries_history SET folder = '' WHERE folder IS NULL;
                ALTER TABLE entries_history ALTER COLUMN folder SET NOT NULL;
                ALTER TABLE entries_history ALTER COLUMN folder SET DEFAULT '';
            END IF;
        END $$;

        DO $$ BEGIN
            IF EXISTS (
                SELECT 1 FROM information_schema.columns
                WHERE table_name = 'entries_history' AND column_name = 'type'
            ) THEN
                UPDATE entries_history SET type = '' WHERE type IS NULL;
                ALTER TABLE entries_history ALTER COLUMN type SET NOT NULL;
                ALTER TABLE entries_history ALTER COLUMN type SET DEFAULT '';
            END IF;
        END $$;

        -- ── Rebuild unique indexes on entries: folder is now part of the key ────────
        -- (user_id, folder, name) allows same name in different folders.
        DROP INDEX IF EXISTS idx_entries_unique_legacy;
        DROP INDEX IF EXISTS idx_entries_unique_user;

        CREATE UNIQUE INDEX IF NOT EXISTS idx_entries_unique_legacy
            ON entries(folder, name)
            WHERE user_id IS NULL;

        CREATE UNIQUE INDEX IF NOT EXISTS idx_entries_unique_user
            ON entries(user_id, folder, name)
            WHERE user_id IS NOT NULL;

        -- ── Replace old namespace/kind indexes ────────────────────────────────────
        DROP INDEX IF EXISTS idx_entries_namespace;
        DROP INDEX IF EXISTS idx_entries_kind;
        DROP INDEX IF EXISTS idx_audit_log_ns_kind;
        DROP INDEX IF EXISTS idx_entries_history_ns_kind_name;

        CREATE INDEX IF NOT EXISTS idx_entries_folder
            ON entries(folder) WHERE folder <> '';
        CREATE INDEX IF NOT EXISTS idx_entries_type
            ON entries(type) WHERE type <> '';
        CREATE INDEX IF NOT EXISTS idx_audit_log_folder_type
            ON audit_log(folder, type);
        CREATE INDEX IF NOT EXISTS idx_entries_history_folder_type_name
            ON entries_history(folder, type, name, version DESC);

        -- ── Drop legacy actor columns ─────────────────────────────────────────────
        ALTER TABLE secrets_history DROP COLUMN IF EXISTS actor;
        ALTER TABLE audit_log DROP COLUMN IF EXISTS actor;
        "#,
    )
    .execute(pool)
    .await?;
    Ok(())
}

async fn restore_plaintext_api_keys(pool: &PgPool) -> Result<()> {
    let has_users_api_key: bool = sqlx::query_scalar(
        "SELECT EXISTS (
            SELECT 1
            FROM information_schema.columns
            WHERE table_schema = 'public'
              AND table_name = 'users'
              AND column_name = 'api_key'
        )",
    )
    .fetch_one(pool)
    .await?;

    if !has_users_api_key {
        sqlx::query("ALTER TABLE users ADD COLUMN api_key TEXT")
            .execute(pool)
            .await?;
        sqlx::query("CREATE UNIQUE INDEX IF NOT EXISTS idx_users_api_key ON users(api_key) WHERE api_key IS NOT NULL")
            .execute(pool)
            .await?;
    }

    let has_api_keys_table: bool = sqlx::query_scalar(
        "SELECT EXISTS (
            SELECT 1
            FROM information_schema.tables
            WHERE table_schema = 'public'
              AND table_name = 'api_keys'
        )",
    )
    .fetch_one(pool)
    .await?;

    if !has_api_keys_table {
        return Ok(());
    }

    #[derive(sqlx::FromRow)]
    struct UserWithoutKey {
        id: uuid::Uuid,
    }

    let users_without_key: Vec<UserWithoutKey> =
        sqlx::query_as("SELECT DISTINCT user_id AS id FROM api_keys WHERE user_id NOT IN (SELECT id FROM users WHERE api_key IS NOT NULL)")
            .fetch_all(pool)
            .await?;

    for user in users_without_key {
        let new_key = crate::service::api_key::generate_api_key();
        sqlx::query("UPDATE users SET api_key = $1 WHERE id = $2")
            .bind(&new_key)
            .bind(user.id)
            .execute(pool)
            .await?;
    }

    sqlx::query("DROP TABLE IF EXISTS api_keys")
        .execute(pool)
        .await?;

    Ok(())
}

// ── Entry-level history snapshot ─────────────────────────────────────────────

pub struct EntrySnapshotParams<'a> {
    pub entry_id: uuid::Uuid,
    pub user_id: Option<uuid::Uuid>,
    pub folder: &'a str,
    pub entry_type: &'a str,
    pub name: &'a str,
    pub version: i64,
    pub action: &'a str,
    pub tags: &'a [String],
    pub metadata: &'a Value,
}

pub async fn snapshot_entry_history(
    tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
    p: EntrySnapshotParams<'_>,
) -> Result<()> {
    sqlx::query(
        "INSERT INTO entries_history \
         (entry_id, folder, type, name, version, action, tags, metadata, user_id) \
         VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)",
    )
    .bind(p.entry_id)
    .bind(p.folder)
    .bind(p.entry_type)
    .bind(p.name)
    .bind(p.version)
    .bind(p.action)
    .bind(p.tags)
    .bind(p.metadata)
    .bind(p.user_id)
    .execute(&mut **tx)
    .await?;
    Ok(())
}

// ── Secret field-level history snapshot ──────────────────────────────────────

pub struct SecretSnapshotParams<'a> {
    pub secret_id: uuid::Uuid,
    pub name: &'a str,
    pub encrypted: &'a [u8],
    pub action: &'a str,
}

pub async fn snapshot_secret_history(
    tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
    p: SecretSnapshotParams<'_>,
) -> Result<()> {
    sqlx::query(
        "INSERT INTO secrets_history \
         (secret_id, name, encrypted, action) \
         VALUES ($1, $2, $3, $4)",
    )
    .bind(p.secret_id)
    .bind(p.name)
    .bind(p.encrypted)
    .bind(p.action)
    .execute(&mut **tx)
    .await?;
    Ok(())
}

// ── DB helpers ────────────────────────────────────────────────────────────────