// Copyright 2026 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 skills

import (
	"fmt"
	"sort"
	"strings"
	"text/template"

	"github.com/googleapis/mcp-toolbox/internal/tools"
	"github.com/googleapis/mcp-toolbox/internal/util/parameters"
)

const skillTemplate = `---
name: {{.SkillName}}
description: {{.SkillDescription}}
---

## Usage

All scripts can be executed using Node.js. Replace ` + "`" + `<param_name>` + "`" + ` and ` + "`" + `<param_value>` + "`" + ` with actual values.

**Bash:**
` + "`" + `node <skill_dir>/scripts/<script_name>.js '{"<param_name>": "<param_value>"}'` + "`" + `

**PowerShell:**
` + "`" + `node <skill_dir>/scripts/<script_name>.js '{\"<param_name>\": \"<param_value>\"}'` + "`" + `
{{if .AdditionalNotes}}
{{.AdditionalNotes}}
{{end}}

## Scripts

{{range .Tools}}
### {{.Name}}

{{.Description}}

{{.ParametersSchema}}

---
{{end}}
`

type toolTemplateData struct {
	Name             string
	Description      string
	ParametersSchema string
}

type skillTemplateData struct {
	SkillName        string
	SkillDescription string
	AdditionalNotes  string
	Tools            []toolTemplateData
}

// generateSkillMarkdown generates the content of the SKILL.md file.
// It includes usage instructions and a reference section for each tool in the skill,
// detailing its description and parameters.
func generateSkillMarkdown(skillName, skillDescription, additionalNotes string, toolsMap map[string]tools.Tool, envVars map[string]string) (string, error) {
	var toolsData []toolTemplateData

	// Order tools based on name
	var toolNames []string
	for name := range toolsMap {
		toolNames = append(toolNames, name)
	}
	sort.Strings(toolNames)

	for _, name := range toolNames {
		tool := toolsMap[name]
		manifest := tool.StaticManifest()

		parametersSchema, err := formatParameters(manifest.Parameters, envVars)
		if err != nil {
			return "", err
		}

		toolsData = append(toolsData, toolTemplateData{
			Name:             name,
			Description:      manifest.Description,
			ParametersSchema: parametersSchema,
		})
	}

	data := skillTemplateData{
		SkillName:        skillName,
		SkillDescription: skillDescription,
		AdditionalNotes:  additionalNotes,
		Tools:            toolsData,
	}

	tmpl, err := template.New("markdown").Parse(skillTemplate)
	if err != nil {
		return "", fmt.Errorf("error parsing markdown template: %w", err)
	}

	var buf strings.Builder
	if err := tmpl.Execute(&buf, data); err != nil {
		return "", fmt.Errorf("error executing markdown template: %w", err)
	}

	return buf.String(), nil
}

const nodeScriptTemplate = `#!/usr/bin/env node
{{if .LicenseHeader}}
{{.LicenseHeader}}
{{end}}
const { spawn, execSync } = require('child_process');
const path = require('path');
const fs = require('fs');
const os = require('os');

const toolName = "{{.Name}}";
const configArgs = [{{.ConfigArgs}}];
{{if .OptionalVars}}
const OPTIONAL_VARS_TO_OMIT_IF_EMPTY = [
{{range .OptionalVars}}    '{{.}}',
{{end}}];
{{end}}

function mergeEnvVars(env) {
	if (process.env.GEMINI_CLI === '1') {
		const envPath = path.resolve(__dirname, '../../../.env');
		if (fs.existsSync(envPath)) {
			const envContent = fs.readFileSync(envPath, 'utf-8');
			envContent.split('\n').forEach(line => {
				const trimmed = line.trim();
				if (trimmed && !trimmed.startsWith('#')) {
					const splitIdx = trimmed.indexOf('=');
					if (splitIdx !== -1) {
						const key = trimmed.slice(0, splitIdx).trim();
						let value = trimmed.slice(splitIdx + 1).trim();
						value = value.replace(/(^['"]|['"]$)/g, '');
						if (env[key] === undefined) {
							env[key] = value;
						}
					}
				}
			});
		}
	} else if (process.env.CLAUDECODE === '1') {
		const prefix = 'CLAUDE_PLUGIN_OPTION_';
		for (const key in process.env) {
			if (key.startsWith(prefix)) {
				env[key.substring(prefix.length)] = process.env[key];
			}
		}
	}
}

function prepareEnvironment() {
	let env = { ...process.env };
	let userAgent = "skills";
	if (process.env.GEMINI_CLI === '1') {
		userAgent = "skills-geminicli";
	} else if (process.env.CLAUDECODE === '1') {
		userAgent = "skills-claudecode";
	} else if (process.env.CODEX_CI === '1') {
        userAgent = "skills-codex";
    }
	mergeEnvVars(env);
	{{if .OptionalVars}}
	OPTIONAL_VARS_TO_OMIT_IF_EMPTY.forEach(varName => {
		if (env[varName] === '') {
			delete env[varName];
		}
	});
	{{end}}

	return { env, userAgent };
}

function main() {
    const { env, userAgent } = prepareEnvironment();
    const args = process.argv.slice(2);
		{{if eq .InvocationMode "npx"}}
		const command = os.platform() === 'win32' ? 'npx.cmd' : 'npx';
		const processedArgs = os.platform() === 'win32' ? args.map(arg => arg.includes('"') ? '"' + arg.replace(/"/g, '""') + '"' : arg) : args;
		const npxArgs = ["--yes", "@toolbox-sdk/server@{{.ToolboxVersion}}", "--log-level", "error", ...configArgs, "invoke", toolName, "--user-agent-metadata", userAgent, ...processedArgs];

		const child = spawn(command, npxArgs, { shell: os.platform() === 'win32', stdio: 'inherit', env });
		{{else}}
		function getToolboxPath() {
				if (process.env.GEMINI_CLI === '1') {
						const ext = process.platform === 'win32' ? '.exe' : '';
						const localPath = path.resolve(__dirname, '../../../toolbox' + ext);
						if (fs.existsSync(localPath)) {
								return localPath;
						}
				}
				try {
						const checkCommand = process.platform === 'win32' ? 'where toolbox' : 'which toolbox';
						const globalPath = execSync(checkCommand, { stdio: 'pipe', encoding: 'utf-8' }).trim();
						if (globalPath) {
								return globalPath.split('\n')[0].trim();
						}
						throw new Error("Toolbox binary not found");
				} catch (e) {
						throw new Error("Toolbox binary not found");
				}
		}

		let toolboxBinary;
		try {
				toolboxBinary = getToolboxPath();
		} catch (err) {
				console.error("Error:", err.message);
				process.exit(1);
		}

		const toolboxArgs = ["--log-level", "error", ...configArgs, "invoke", toolName, "--user-agent-metadata", userAgent, ...args];
		const child = spawn(toolboxBinary, toolboxArgs, { stdio: 'inherit', env });
		{{end}}

    child.on('close', (code) => {
        process.exit(code);
    });

    child.on('error', (err) => {
        console.error("Error executing toolbox:", err);
        process.exit(1);
    });
}

main();
`

type scriptData struct {
	Name           string
	ConfigArgs     string
	LicenseHeader  string
	InvocationMode string
	ToolboxVersion string
	OptionalVars   []string
}

// generateScriptContent creates the content for a Node.js wrapper script.
// This script invokes the toolbox CLI with the appropriate configuration
// (using a generated config) and arguments to execute the specific tool.
func generateScriptContent(name string, configArgs string, licenseHeader string, mode string, version string, optionalVars []string) (string, error) {
	data := scriptData{
		Name:           name,
		ConfigArgs:     configArgs,
		LicenseHeader:  licenseHeader,
		InvocationMode: mode,
		ToolboxVersion: version,
		OptionalVars:   optionalVars,
	}

	tmpl, err := template.New("script").Parse(nodeScriptTemplate)
	if err != nil {
		return "", fmt.Errorf("error parsing script template: %w", err)
	}

	var buf strings.Builder
	if err := tmpl.Execute(&buf, data); err != nil {
		return "", fmt.Errorf("error executing script template: %w", err)
	}

	return buf.String(), nil
}

// formatParameters converts a list of parameter manifests into a formatted JSON schema string.
// This schema is used in the skill documentation to describe the input parameters for a tool.
func formatParameters(params []parameters.ParameterManifest, envVars map[string]string) (string, error) {
	if len(params) == 0 {
		return "", nil
	}

	var sb strings.Builder
	sb.WriteString("#### Parameters\n\n")
	sb.WriteString("| Name | Type | Description | Required | Default |\n")
	sb.WriteString("| :--- | :--- | :--- | :--- | :--- |\n")

	for _, p := range params {
		required := "No"
		if p.Required {
			required = "Yes"
		}
		defaultValue := ""
		if p.Default != nil {
			defaultValue = fmt.Sprintf("`%v`", p.Default)
			// Check if default value matches any env var
			if strVal, ok := p.Default.(string); ok {
				for _, envVal := range envVars {
					if envVal == strVal {
						defaultValue = ""
						break
					}
				}
			}
		}
		fmt.Fprintf(&sb, "| %s | %s | %s | %s | %s |\n", p.Name, p.Type, p.Description, required, defaultValue)
	}

	return sb.String(), nil
}