// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package postgreslistquerystats

import (
	"context"
	"fmt"

	yaml "github.com/goccy/go-yaml"
	"github.com/googleapis/genai-toolbox/internal/embeddingmodels"
	"github.com/googleapis/genai-toolbox/internal/sources"
	"github.com/googleapis/genai-toolbox/internal/tools"
	"github.com/googleapis/genai-toolbox/internal/util/parameters"
	"github.com/jackc/pgx/v5/pgxpool"
)

const kind string = "postgres-list-query-stats"

const listQueryStats = `
	SELECT
          d.datname,
          s.query,
          s.calls,
          s.total_exec_time,
          s.min_exec_time,
          s.max_exec_time,
          s.mean_exec_time,
          s.rows,
          s.shared_blks_hit,
          s.shared_blks_read
      FROM
          pg_stat_statements s
      JOIN pg_database d ON d.oid = s.dbid
      WHERE d.datname <> 'cloudsqladmin' AND ($1::text IS NULL OR d.datname LIKE '%' || $1::text || '%')
      ORDER BY total_exec_time DESC
      LIMIT COALESCE($2::int, 50);
`

func init() {
	if !tools.Register(kind, newConfig) {
		panic(fmt.Sprintf("tool kind %q already registered", kind))
	}
}

func newConfig(ctx context.Context, name string, decoder *yaml.Decoder) (tools.ToolConfig, error) {
	actual := Config{Name: name}
	if err := decoder.DecodeContext(ctx, &actual); err != nil {
		return nil, err
	}
	return actual, nil
}

type compatibleSource interface {
	PostgresPool() *pgxpool.Pool
	RunSQL(context.Context, string, []any) (any, error)
}

type Config struct {
	Name         string   `yaml:"name" validate:"required"`
	Kind         string   `yaml:"kind" validate:"required"`
	Source       string   `yaml:"source" validate:"required"`
	Description  string   `yaml:"description"`
	AuthRequired []string `yaml:"authRequired"`
}

// validate interface
var _ tools.ToolConfig = Config{}

func (cfg Config) ToolConfigKind() string {
	return kind
}

func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error) {
	allParameters := parameters.Parameters{
		parameters.NewStringParameterWithDefault("database_name", "", "Optional: The database name to list query stats for."),
		parameters.NewIntParameterWithDefault("limit", 50, "Optional: The maximum number of results to return. Defaults to 50."),
	}
	paramManifest := allParameters.Manifest()

	if cfg.Description == "" {
		cfg.Description = "Lists performance statistics for executed queries ordered by total time, filtering by database name pattern if provided. This tool requires the pg_stat_statements extension to be installed. The tool returns the database name, query text, execution count, timing metrics (total, min, max, mean), rows affected, and buffer cache I/O statistics (hits and reads)."
	}

	mcpManifest := tools.GetMcpManifest(cfg.Name, cfg.Description, cfg.AuthRequired, allParameters, nil)

	// finish tool setup
	return Tool{
		Config:    cfg,
		allParams: allParameters,
		manifest: tools.Manifest{
			Description:  cfg.Description,
			Parameters:   paramManifest,
			AuthRequired: cfg.AuthRequired,
		},
		mcpManifest: mcpManifest,
	}, nil
}

// validate interface
var _ tools.Tool = Tool{}

type Tool struct {
	Config
	allParams   parameters.Parameters `yaml:"allParams"`
	manifest    tools.Manifest
	mcpManifest tools.McpManifest
}

func (t Tool) ToConfig() tools.ToolConfig {
	return t.Config
}

func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, params parameters.ParamValues, accessToken tools.AccessToken) (any, error) {
	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Source, t.Name, t.Kind)
	if err != nil {
		return nil, err
	}
	paramsMap := params.AsMap()

	newParams, err := parameters.GetParams(t.allParams, paramsMap)
	if err != nil {
		return nil, fmt.Errorf("unable to extract standard params %w", err)
	}
	sliceParams := newParams.AsSlice()
	return source.RunSQL(ctx, listQueryStats, sliceParams)
}

func (t Tool) ParseParams(data map[string]any, claims map[string]map[string]any) (parameters.ParamValues, error) {
	return parameters.ParseParams(t.allParams, data, claims)
}

func (t Tool) EmbedParams(ctx context.Context, paramValues parameters.ParamValues, embeddingModelsMap map[string]embeddingmodels.EmbeddingModel) (parameters.ParamValues, error) {
	return parameters.EmbedParams(ctx, t.allParams, paramValues, embeddingModelsMap, nil)
}

func (t Tool) Manifest() tools.Manifest {
	return t.manifest
}

func (t Tool) McpManifest() tools.McpManifest {
	return t.mcpManifest
}

func (t Tool) Authorized(verifiedAuthServices []string) bool {
	return tools.IsAuthorized(t.AuthRequired, verifiedAuthServices)
}

func (t Tool) RequiresClientAuthorization(resourceMgr tools.SourceProvider) (bool, error) {
	return false, nil
}

func (t Tool) GetAuthTokenHeaderName(resourceMgr tools.SourceProvider) (string, error) {
	return "Authorization", nil
}
