// 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 redis

import (
	"context"
	"fmt"
	"net/http"

	yaml "github.com/goccy/go-yaml"
	redissrc "github.com/googleapis/mcp-toolbox/internal/sources/redis"
	"github.com/googleapis/mcp-toolbox/internal/tools"
	"github.com/googleapis/mcp-toolbox/internal/util"
	"github.com/googleapis/mcp-toolbox/internal/util/parameters"
)

const resourceType string = "redis"

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

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

type compatibleSource interface {
	RedisClient() redissrc.RedisClient
	RunCommand(context.Context, [][]any) (any, error)
}

type Config struct {
	tools.ConfigBase `yaml:",inline"`
	Type             string                 `yaml:"type" validate:"required"`
	Source           string                 `yaml:"source" validate:"required"`
	Commands         [][]string             `yaml:"commands" validate:"required"`
	Parameters       parameters.Parameters  `yaml:"parameters"`
	Annotations      *tools.ToolAnnotations `yaml:"annotations,omitempty"`
}

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

func (cfg Config) ToolConfigType() string {
	return resourceType
}

func (cfg Config) Initialize(context.Context) (tools.Tool, error) {
	if cfg.Description == "" {
		return nil, fmt.Errorf("description is required for tool %q", cfg.Name)
	}

	return Tool{
		BaseTool: tools.NewBaseTool(
			cfg,
			tools.GetAnnotationsOrDefault(cfg.Annotations, tools.NewDestructiveAnnotations),
			tools.Manifest{Description: cfg.Description, Parameters: cfg.Parameters.Manifest(), AuthRequired: cfg.AuthRequired},
			cfg.Parameters,
		),
	}, nil
}

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

type Tool struct {
	tools.BaseTool[Config]
}

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

func (t Tool) Invoke(ctx context.Context, resourceMgr tools.SourceProvider, params parameters.ParamValues, accessToken tools.AccessToken) (any, util.ToolboxError) {
	source, err := tools.GetCompatibleSource[compatibleSource](resourceMgr, t.Cfg.Source, t.Cfg.Name, t.Cfg.Type)
	if err != nil {
		return nil, util.NewClientServerError("source used is not compatible with the tool", http.StatusInternalServerError, err)
	}

	cmds, err := replaceCommandsParams(t.Cfg.Commands, t.Cfg.Parameters, params)
	if err != nil {
		return nil, util.NewAgentError("error replacing commands' parameters", err)
	}
	resp, err := source.RunCommand(ctx, cmds)
	if err != nil {
		return nil, util.ProcessGeneralError(err)
	}
	return resp, nil
}

// replaceCommandsParams is a helper function to replace parameters in the commands

func replaceCommandsParams(commands [][]string, params parameters.Parameters, paramValues parameters.ParamValues) ([][]any, error) {
	paramMap := paramValues.AsMapWithDollarPrefix()
	typeMap := make(map[string]string, len(params))
	for _, p := range params {
		placeholder := "$" + p.GetName()
		typeMap[placeholder] = p.GetType()
	}
	newCommands := make([][]any, len(commands))
	for i, cmd := range commands {
		newCmd := make([]any, 0)
		for _, part := range cmd {
			v, ok := paramMap[part]
			if !ok {
				// Command part is not a Parameter placeholder
				newCmd = append(newCmd, part)
				continue
			}
			if typeMap[part] == "array" {
				for _, item := range v.([]any) {
					// Nested arrays will only be expanded once
					// e.g., [A, [B, C]]  --> ["A", "[B C]"]
					newCmd = append(newCmd, fmt.Sprintf("%s", item))
				}
				continue
			}
			newCmd = append(newCmd, fmt.Sprintf("%s", v))
		}
		newCommands[i] = newCmd
	}
	return newCommands, nil
}