// Package destroy handles tearing down obm deployments.
package destroy

import (
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"github.com/openboatmobile/obm/internal/prompt"
)

// Options configures the destroy operation.
type Options struct {
	WorkDir     string   // Working directory (default: current)
	AutoApprove bool     // Skip confirmation prompt
	VarFiles    []string // Additional var files to load
	EnvFiles    []string // Additional env files to load
	KeepState   bool     // Don't delete state files after destroy
}

// Result holds the outcome of a destroy operation.
type Result struct {
	Resources []Resource // Resources that were destroyed
	Duration   string    // How long the operation took
}

// Resource represents a single destroyed resource.
type Resource struct {
	Address string // e.g., "hcloud_server.main"
	Type    string // e.g., "hcloud_server"
	Name    string // e.g., "main"
}

// State represents the terraform.tfstate structure (minimal fields for resource extraction).
type State struct {
	Resources []StateResource `json:"resources"`
}

// StateResource is a resource entry in terraform state.
type StateResource struct {
	Address string            `json:"address"`
	Type    string            `json:"type"`
	Name    string            `json:"name"`
	Module  string            `json:"module,omitempty"`
}

// Run executes the destroy workflow.
func Run(opts *Options) error {
	if opts == nil {
		opts = &Options{}
	}

	// Determine working directory
	workDir := opts.WorkDir
	if workDir == "" {
		cwd, err := os.Getwd()
		if err != nil {
			return fmt.Errorf("getting current directory: %w", err)
		}
		workDir = cwd
	}

	// Check for terraform files
	tfDir := filepath.Join(workDir, ".terraform")
	tfState := filepath.Join(workDir, "terraform.tfstate")

	if !fileExists(tfState) && !dirExists(tfDir) {
		prompt.Warn("No Terraform state found in " + workDir)
		prompt.Info("Run 'obm deploy' first to create infrastructure")
		return nil
	}

	// Load and display resources that will be destroyed
	resources, err := listResourcesFromState(tfState)
	if err != nil {
		prompt.Warn("Could not read state: " + err.Error())
		prompt.Info("Proceeding with destroy anyway...")
		resources = []Resource{}
	}

	// Display what will be destroyed
	displayDestroyPlan(resources)

	// Confirmation
	if !opts.AutoApprove {
		if !prompt.Confirm("This will destroy all listed resources. Continue?", false) {
			prompt.Info("Destroy cancelled")
			return nil
		}
	}

	// Run terraform destroy
	prompt.Header("🔧 Destroying Infrastructure")
	if err := runTerraformDestroy(workDir, opts); err != nil {
		return fmt.Errorf("terraform destroy failed: %w", err)
	}

	prompt.Success("Infrastructure destroyed successfully")

	// Clean up state files unless asked to keep
	if !opts.KeepState {
		cleanupStateFiles(workDir)
	}

	return nil
}

// listResourcesFromState extracts resources from terraform.tfstate.
func listResourcesFromState(statePath string) ([]Resource, error) {
	data, err := os.ReadFile(statePath)
	if err != nil {
		return nil, fmt.Errorf("reading state: %w", err)
	}

	// Handle empty state file
	if len(data) == 0 {
		return nil, nil
	}

	var state State
	// Try parsing as JSON
	var rawState map[string]interface{}
	if err := json.Unmarshal(data, &rawState); err != nil {
		return nil, fmt.Errorf("parsing state JSON: %w", err)
	}

	// Handle different state file versions
	if resources, ok := rawState["resources"].([]interface{}); ok {
		for _, r := range resources {
			if resMap, ok := r.(map[string]interface{}); ok {
				res := Resource{}
				if addr, ok := resMap["address"].(string); ok {
					res.Address = addr
				}
				if t, ok := resMap["type"].(string); ok {
					res.Type = t
				}
				if n, ok := resMap["name"].(string); ok {
					res.Name = n
				}
				// Handle module path
				if module, ok := resMap["module"].(string); ok && module != "" {
					res.Address = module + "." + res.Address
				}
				state.Resources = append(state.Resources, StateResource{
					Address: res.Address,
					Type:    res.Type,
					Name:    res.Name,
				})
			}
		}
	}

	result := make([]Resource, 0, len(state.Resources))
	for _, sr := range state.Resources {
		result = append(result, Resource{
			Address: sr.Address,
			Type:    sr.Type,
			Name:    sr.Name,
		})
	}

	return result, nil
}

// displayDestroyPlan shows what will be destroyed.
func displayDestroyPlan(resources []Resource) {
	prompt.Header("⚠️  Destroy Plan")
	prompt.Divider()

	if len(resources) == 0 {
		prompt.Info("No managed resources found in state")
		prompt.Warn("Terraform may still destroy resources tracked remotely")
		return
	}

	// Group by type
	byType := make(map[string][]Resource)
	for _, r := range resources {
		byType[r.Type] = append(byType[r.Type], r)
	}

	fmt.Printf("\n  %-25s %s\n", "Resource Type", "Count")
	fmt.Printf("  %-25s %s\n", "─────────────", "─────")
	for typ, res := range byType {
		fmt.Printf("  %-25s %d\n", typ, len(res))
	}
	prompt.Divider()

	fmt.Printf("\n  Total resources to destroy: %d\n\n", len(resources))

	for _, r := range resources {
		fmt.Printf("  - %s\n", r.Address)
	}
	fmt.Println()
}

// runTerraformDestroy executes terraform destroy.
func runTerraformDestroy(workDir string, opts *Options) error {
	args := []string{"destroy", "-auto-approve"}

	// Add var files
	for _, vf := range opts.VarFiles {
		args = append(args, "-var-file", vf)
	}

	cmd := exec.Command("terraform", args...)
	cmd.Dir = workDir

	// Stream output to stdout/stderr
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr

	// Load environment from env files
	env := os.Environ()
	for _, ef := range opts.EnvFiles {
		envVars, err := loadEnvFile(ef)
		if err != nil {
			prompt.Warn("Could not load env file " + ef + ": " + err.Error())
			continue
		}
		env = append(env, envVars...)
	}
	cmd.Env = env

	return cmd.Run()
}

// loadEnvFile reads a .env file and returns KEY=value strings.
func loadEnvFile(path string) ([]string, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}

	var result []string
	lines := strings.Split(string(data), "\n")
	for _, line := range lines {
		line = strings.TrimSpace(line)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		// Basic KEY=value parsing (handle quoted values)
		parts := strings.SplitN(line, "=", 2)
		if len(parts) == 2 {
			key := strings.TrimSpace(parts[0])
			value := strings.TrimSpace(parts[1])
			// Remove surrounding quotes
			if len(value) >= 2 && (value[0] == '"' || value[0] == '\'') && value[0] == value[len(value)-1] {
				value = value[1 : len(value)-1]
			}
			result = append(result, fmt.Sprintf("%s=%s", key, value))
		}
	}
	return result, nil
}

// cleanupStateFiles removes terraform state files after successful destroy.
func cleanupStateFiles(workDir string) {
	stateFiles := []string{
		"terraform.tfstate",
		"terraform.tfstate.backup",
		"terraform.tfstate.backup-info",
	}

	// Remove state files
	for _, f := range stateFiles {
		path := filepath.Join(workDir, f)
		if fileExists(path) {
			if err := os.Remove(path); err != nil {
				prompt.Warn("Could not remove " + f + ": " + err.Error())
			} else {
				prompt.Info("Removed " + f)
			}
		}
	}

	// Remove .terraform directory
	tfDir := filepath.Join(workDir, ".terraform")
	if dirExists(tfDir) {
		if err := os.RemoveAll(tfDir); err != nil {
			prompt.Warn("Could not remove .terraform: " + err.Error())
		} else {
			prompt.Info("Removed .terraform directory")
		}
	}

	// Remove .terraform.lock.hcl
	lockFile := filepath.Join(workDir, ".terraform.lock.hcl")
	if fileExists(lockFile) {
		if err := os.Remove(lockFile); err != nil {
			prompt.Warn("Could not remove .terraform.lock.hcl: " + err.Error())
		} else {
			prompt.Info("Removed .terraform.lock.hcl")
		}
	}
}

// fileExists returns true if the path is an existing file.
func fileExists(path string) bool {
	info, err := os.Stat(path)
	return err == nil && !info.IsDir()
}

// dirExists returns true if the path is an existing directory.
func dirExists(path string) bool {
	info, err := os.Stat(path)
	return err == nil && info.IsDir()
}