local str = require("string")
local tbl = require("table")
local sqlite = {}

local Connection = {}
Connection.__index = Connection

function Connection:close()
	if self._id then
		local ok = moonshark.sql_close(self._id)
		self._id = nil
		return ok
	end
	return false
end

function Connection:ping()
	if not self._id then
		error("Connection is closed")
	end
	return moonshark.sql_ping(self._id)
end

function Connection:query(query_str, ...)
	if not self._id then
		error("Connection is closed")
	end
	query_str = str.normalize_whitespace(query_str)
	return moonshark.sql_query(self._id, query_str, ...)
end

function Connection:exec(query_str, ...)
	if not self._id then
		error("Connection is closed")
	end
	query_str = str.normalize_whitespace(query_str)
	return moonshark.sql_exec(self._id, query_str, ...)
end

function Connection:query_row(query_str, ...)
	local results = self:query(query_str, ...)
	if results and #results > 0 then
		return results[1]
	end
	return nil
end

function Connection:query_value(query_str, ...)
	local row = self:query_row(query_str, ...)
	if row then
		for _, value in pairs(row) do
			return value
		end
	end
	return nil
end

-- Enhanced transaction support
function Connection:begin()
	local result = self:exec("BEGIN")
	if result then
		return {
			conn = self,
			active = true,

			commit = function(tx)
				if tx.active then
					local result = tx.conn:exec("COMMIT")
					tx.active = false
					return result
				end
				return false
			end,

			rollback = function(tx)
				if tx.active then
					local result = tx.conn:exec("ROLLBACK")
					tx.active = false
					return result
				end
				return false
			end,

			query = function(tx, query_str, ...)
				if not tx.active then
					error("Transaction is not active")
				end
				return tx.conn:query(query_str, ...)
			end,

			exec = function(tx, query_str, ...)
				if not tx.active then
					error("Transaction is not active")
				end
				return tx.conn:exec(query_str, ...)
			end,

			query_row = function(tx, query_str, ...)
				if not tx.active then
					error("Transaction is not active")
				end
				return tx.conn:query_row(query_str, ...)
			end,

			query_value = function(tx, query_str, ...)
				if not tx.active then
					error("Transaction is not active")
				end
				return tx.conn:query_value(query_str, ...)
			end
		}
	end
	return nil
end

-- Simplified query builders using table utilities
function Connection:insert(table_name, data)
	if str.is_blank(table_name) then
		error("Table name cannot be empty")
	end

	local keys = tbl.keys(data)
	local values = tbl.values(data)
	local placeholders = tbl.map(keys, function() return "?" end)

	local query = str.template("INSERT INTO ${table} (${columns}) VALUES (${placeholders})", {
		table = table_name,
		columns = tbl.concat(keys, ", "),
		placeholders = tbl.concat(placeholders, ", ")
	})

	return self:exec(query, unpack(values))
end

function Connection:upsert(table_name, data, conflict_columns)
	if str.is_blank(table_name) then
		error("Table name cannot be empty")
	end

	local keys = tbl.keys(data)
	local values = tbl.values(data)
	local placeholders = tbl.map(keys, function() return "?" end)
	local updates = tbl.map(keys, function(key)
		return str.template("${key} = excluded.${key}", {key = key})
	end)

	local conflict_clause = ""
	if conflict_columns then
		if type(conflict_columns) == "string" then
			conflict_clause = str.template("(${columns})", {columns = conflict_columns})
		else
			conflict_clause = str.template("(${columns})", {columns = tbl.concat(conflict_columns, ", ")})
		end
	end

	local query = str.template("INSERT INTO ${table} (${columns}) VALUES (${placeholders}) ON CONFLICT ${conflict} DO UPDATE SET ${updates}", {
		table = table_name,
		columns = tbl.concat(keys, ", "),
		placeholders = tbl.concat(placeholders, ", "),
		conflict = conflict_clause,
		updates = tbl.concat(updates, ", ")
	})

	return self:exec(query, unpack(values))
end

function Connection:update(table_name, data, where_clause, ...)
	if str.is_blank(table_name) then
		error("Table name cannot be empty")
	end
	if str.is_blank(where_clause) then
		error("WHERE clause cannot be empty for UPDATE")
	end

	local keys = tbl.keys(data)
	local values = tbl.values(data)
	local sets = tbl.map(keys, function(key)
		return str.template("${key} = ?", {key = key})
	end)

	local query = str.template("UPDATE ${table} SET ${sets} WHERE ${where}", {
		table = table_name,
		sets = tbl.concat(sets, ", "),
		where = where_clause
	})

	-- Add WHERE clause parameters
	local where_args = {...}
	tbl.extend(values, where_args)

	return self:exec(query, unpack(values))
end

function Connection:delete(table_name, where_clause, ...)
	if str.is_blank(table_name) then
		error("Table name cannot be empty")
	end
	if str.is_blank(where_clause) then
		error("WHERE clause cannot be empty for DELETE")
	end

	local query = str.template("DELETE FROM ${table} WHERE ${where}", {
		table = table_name,
		where = where_clause
	})
	return self:exec(query, ...)
end

function Connection:select(table_name, columns, where_clause, ...)
	if str.is_blank(table_name) then
		error("Table name cannot be empty")
	end

	columns = columns or "*"
	if type(columns) == "table" then
		columns = tbl.concat(columns, ", ")
	end

	local query
	if where_clause and not str.is_blank(where_clause) then
		query = str.template("SELECT ${columns} FROM ${table} WHERE ${where}", {
			columns = columns,
			table = table_name,
			where = where_clause
		})
		return self:query(query, ...)
	else
		query = str.template("SELECT ${columns} FROM ${table}", {
			columns = columns,
			table = table_name
		})
		return self:query(query)
	end
end

-- Schema helpers
function Connection:table_exists(table_name)
	if str.is_blank(table_name) then
		return false
	end

	local result = self:query_value(
		"SELECT name FROM sqlite_master WHERE type='table' AND name=?",
		str.trim(table_name)
	)
	return result ~= nil
end

function Connection:column_exists(table_name, column_name)
	if str.is_blank(table_name) or str.is_blank(column_name) then
		return false
	end

	local result = self:query(str.template("PRAGMA table_info(${table})", {table = table_name}))
	if result then
		return tbl.any(result, function(row)
			return str.iequals(row.name, str.trim(column_name))
		end)
	end
	return false
end

function Connection:create_table(table_name, schema)
	if str.is_blank(table_name) or str.is_blank(schema) then
		error("Table name and schema cannot be empty")
	end

	local query = str.template("CREATE TABLE IF NOT EXISTS ${table} (${schema})", {
		table = table_name,
		schema = str.trim(schema)
	})
	return self:exec(query)
end

function Connection:drop_table(table_name)
	if str.is_blank(table_name) then
		error("Table name cannot be empty")
	end

	local query = str.template("DROP TABLE IF EXISTS ${table}", {table = table_name})
	return self:exec(query)
end

function Connection:add_column(table_name, column_def)
	if str.is_blank(table_name) or str.is_blank(column_def) then
		error("Table name and column definition cannot be empty")
	end

	local query = str.template("ALTER TABLE ${table} ADD COLUMN ${column}", {
		table = table_name,
		column = str.trim(column_def)
	})
	return self:exec(query)
end

function Connection:create_index(index_name, table_name, columns, unique)
	if str.is_blank(index_name) or str.is_blank(table_name) then
		error("Index name and table name cannot be empty")
	end

	local unique_clause = unique and "UNIQUE " or ""
	local columns_str = type(columns) == "table" and tbl.concat(columns, ", ") or tostring(columns)

	local query = str.template("CREATE ${unique}INDEX IF NOT EXISTS ${index} ON ${table} (${columns})", {
		unique = unique_clause,
		index = index_name,
		table = table_name,
		columns = columns_str
	})
	return self:exec(query)
end

function Connection:drop_index(index_name)
	if str.is_blank(index_name) then
		error("Index name cannot be empty")
	end

	local query = str.template("DROP INDEX IF EXISTS ${index}", {index = index_name})
	return self:exec(query)
end

-- SQLite-specific functions
function Connection:vacuum()
	return self:exec("VACUUM")
end

function Connection:analyze()
	return self:exec("ANALYZE")
end

function Connection:integrity_check()
	return self:query("PRAGMA integrity_check")
end

function Connection:foreign_keys(enabled)
	local value = enabled and "ON" or "OFF"
	return self:exec(str.template("PRAGMA foreign_keys = ${value}", {value = value}))
end

function Connection:journal_mode(mode)
	mode = mode or "WAL"
	local valid_modes = {"DELETE", "TRUNCATE", "PERSIST", "MEMORY", "WAL", "OFF"}

	if not tbl.contains(tbl.map(valid_modes, str.upper), str.upper(mode)) then
		error("Invalid journal mode: " .. mode)
	end

	return self:query(str.template("PRAGMA journal_mode = ${mode}", {mode = str.upper(mode)}))
end

function Connection:synchronous(level)
	level = level or "NORMAL"
	local valid_levels = {"OFF", "NORMAL", "FULL", "EXTRA"}

	if not tbl.contains(valid_levels, str.upper(level)) then
		error("Invalid synchronous level: " .. level)
	end

	return self:exec(str.template("PRAGMA synchronous = ${level}", {level = str.upper(level)}))
end

function Connection:cache_size(size)
	size = size or -64000
	if type(size) ~= "number" then
		error("Cache size must be a number")
	end
	return self:exec(str.template("PRAGMA cache_size = ${size}", {size = tostring(size)}))
end

function Connection:temp_store(mode)
	mode = mode or "MEMORY"
	local valid_modes = {"DEFAULT", "FILE", "MEMORY"}

	if not tbl.contains(valid_modes, str.upper(mode)) then
		error("Invalid temp_store mode: " .. mode)
	end

	return self:exec(str.template("PRAGMA temp_store = ${mode}", {mode = str.upper(mode)}))
end

-- Connection management
function sqlite.open(database_path)
	database_path = database_path or ":memory:"

	if database_path ~= ":memory:" then
		database_path = str.trim(database_path)
		if str.is_blank(database_path) then
			database_path = ":memory:"
		end
	end

	local conn_id = moonshark.sql_connect("sqlite", database_path)
	if conn_id then
		local conn = {_id = conn_id}
		setmetatable(conn, Connection)
		return conn
	end
	return nil
end

sqlite.connect = sqlite.open

-- Quick execution functions
function sqlite.query(database_path, query_str, ...)
	local conn = sqlite.open(database_path)
	if not conn then
		error(str.template("Failed to open SQLite database: ${path}", {
			path = database_path or ":memory:"
		}))
	end

	local results = conn:query(query_str, ...)
	conn:close()
	return results
end

function sqlite.exec(database_path, query_str, ...)
	local conn = sqlite.open(database_path)
	if not conn then
		error(str.template("Failed to open SQLite database: ${path}", {
			path = database_path or ":memory:"
		}))
	end

	local result = conn:exec(query_str, ...)
	conn:close()
	return result
end

function sqlite.query_row(database_path, query_str, ...)
	local results = sqlite.query(database_path, query_str, ...)
	if results and #results > 0 then
		return results[1]
	end
	return nil
end

function sqlite.query_value(database_path, query_str, ...)
	local row = sqlite.query_row(database_path, query_str, ...)
	if row then
		for _, value in pairs(row) do
			return value
		end
	end
	return nil
end

-- Migration helpers
function sqlite.migrate(database_path, migrations)
	local conn = sqlite.open(database_path)
	if not conn then
		error("Failed to open SQLite database for migration")
	end

	conn:create_table("_migrations",
		"id INTEGER PRIMARY KEY, name TEXT UNIQUE, applied_at DATETIME DEFAULT CURRENT_TIMESTAMP")

	local tx = conn:begin()
	if not tx then
		conn:close()
		error("Failed to begin migration transaction")
	end

	local success = true
	local error_msg = ""

	for _, migration in ipairs(migrations) do
		if not migration.name or str.is_blank(migration.name) then
			error_msg = "Migration must have a non-empty name"
			success = false
			break
		end

		local existing = conn:query_value("SELECT id FROM _migrations WHERE name = ?",
			str.trim(migration.name))
		if not existing then
			local ok, err = pcall(function()
				if type(migration.up) == "string" then
					conn:exec(migration.up)
				elseif type(migration.up) == "function" then
					migration.up(conn)
				else
					error("Migration 'up' must be string or function")
				end
			end)

			if ok then
				conn:exec("INSERT INTO _migrations (name) VALUES (?)", str.trim(migration.name))
				print(str.template("Applied migration: ${name}", {name = migration.name}))
			else
				success = false
				error_msg = str.template("Migration '${name}' failed: ${error}", {
					name = migration.name,
					error = err or "unknown error"
				})
				break
			end
		end
	end

	if success then
		tx:commit()
	else
		tx:rollback()
		conn:close()
		error(error_msg)
	end

	conn:close()
	return true
end

-- Simplified result processing using table utilities
function sqlite.to_array(results, column_name)
	if not results or tbl.is_empty(results) then
		return {}
	end

	if str.is_blank(column_name) then
		error("Column name cannot be empty")
	end

	return tbl.map(results, function(row) return row[column_name] end)
end

function sqlite.to_map(results, key_column, value_column)
	if not results or tbl.is_empty(results) then
		return {}
	end

	if str.is_blank(key_column) then
		error("Key column name cannot be empty")
	end

	local map = {}
	for _, row in ipairs(results) do
		local key = row[key_column]
		map[key] = value_column and row[value_column] or row
	end
	return map
end

function sqlite.group_by(results, column_name)
	if not results or tbl.is_empty(results) then
		return {}
	end

	if str.is_blank(column_name) then
		error("Column name cannot be empty")
	end

	return tbl.group_by(results, function(row) return row[column_name] end)
end

-- Simplified debug helper
function sqlite.print_results(results)
	if not results or tbl.is_empty(results) then
		print("No results")
		return
	end

	local columns = tbl.keys(results[1])
	tbl.sort(columns)

	-- Calculate column widths
	local widths = tbl.map_values(tbl.to_map(columns, function(col) return col end, function(col) return str.length(col) end), function(width) return width end)

	for _, row in ipairs(results) do
		for _, col in ipairs(columns) do
			local value = tostring(row[col] or "")
			widths[col] = math.max(widths[col], str.length(value))
		end
	end

	-- Print header
	local header_parts = tbl.map(columns, function(col) return str.pad_right(col, widths[col]) end)
	local separator_parts = tbl.map(columns, function(col) return str.repeat_("-", widths[col]) end)

	print(tbl.concat(header_parts, " | "))
	print(tbl.concat(separator_parts, "-+-"))

	-- Print rows
	for _, row in ipairs(results) do
		local value_parts = tbl.map(columns, function(col)
			local value = tostring(row[col] or "")
			return str.pad_right(value, widths[col])
		end)
		print(tbl.concat(value_parts, " | "))
	end
end

return sqlite