//go:build darwin
// +build darwin

package platform

import (
	"fmt"
	"path/filepath"
	"strings"

	"github.com/safedep/pmg/sandbox"
	"github.com/safedep/pmg/sandbox/util"
)

// policyTranslator translates PMG sandbox policies to Seatbelt Profile Language (.sb).
type policyTranslator struct{}

// newPolicyTranslator creates a new policy translator.
func newPolicyTranslator() *policyTranslator {
	return &policyTranslator{}
}

// translate converts a PMG SandboxPolicy to Seatbelt Profile Language.
func (t *policyTranslator) translate(policy *sandbox.SandboxPolicy) (string, error) {
	var sb strings.Builder

	// Header
	sb.WriteString("(version 1)\n")
	sb.WriteString(fmt.Sprintf(";; PMG Sandbox Policy: %s\n", policy.Name))
	sb.WriteString(fmt.Sprintf(";; %s\n", policy.Description))
	sb.WriteString(";; Generated by PMG sandbox system\n\n")

	// Default policy: deny by default for maximum security
	sb.WriteString("(deny default)\n\n")

	// Allow basic system operations required for any process
	sb.WriteString(";; Basic system access\n")
	sb.WriteString("(allow process-fork)\n")
	sb.WriteString("(allow process-exec-interpreter)\n")
	sb.WriteString("(allow sysctl-read)\n")
	sb.WriteString("(allow mach-lookup)\n")
	sb.WriteString("(allow mach-register)\n")
	sb.WriteString("(allow ipc-posix-shm)\n")
	sb.WriteString("(allow signal)\n\n")

	// Filesystem rules
	if err := t.translateFilesystem(policy, &sb); err != nil {
		return "", fmt.Errorf("failed to translate filesystem rules: %w", err)
	}

	// Network rules
	if err := t.translateNetwork(policy, &sb); err != nil {
		return "", fmt.Errorf("failed to translate network rules: %w", err)
	}

	// Process execution rules
	if err := t.translateProcess(policy, &sb); err != nil {
		return "", fmt.Errorf("failed to translate process rules: %w", err)
	}

	return sb.String(), nil
}

// translateFilesystem translates filesystem access rules.
func (t *policyTranslator) translateFilesystem(policy *sandbox.SandboxPolicy, sb *strings.Builder) error {
	sb.WriteString(";; Filesystem access\n")

	// Expand and add allow read rules
	for _, pattern := range policy.Filesystem.AllowRead {
		expanded, err := util.ExpandVariables(pattern)
		if err != nil {
			return fmt.Errorf("failed to expand pattern %s: %w", pattern, err)
		}

		// Handle glob patterns vs literal paths
		if util.ContainsGlob(expanded) {
			// For glob patterns, use subpath with the base directory
			baseDir := filepath.Dir(strings.TrimSuffix(expanded, "/**"))
			sb.WriteString(fmt.Sprintf("(allow file-read* (subpath \"%s\"))\n", baseDir))
		} else {
			sb.WriteString(fmt.Sprintf("(allow file-read* (subpath \"%s\"))\n", expanded))
		}
	}

	sb.WriteString("\n")

	// Expand and add allow write rules
	for _, pattern := range policy.Filesystem.AllowWrite {
		expanded, err := util.ExpandVariables(pattern)
		if err != nil {
			return fmt.Errorf("failed to expand pattern %s: %w", pattern, err)
		}

		if util.ContainsGlob(expanded) {
			baseDir := filepath.Dir(strings.TrimSuffix(expanded, "/**"))
			sb.WriteString(fmt.Sprintf("(allow file-write* (subpath \"%s\"))\n", baseDir))
		} else {
			sb.WriteString(fmt.Sprintf("(allow file-write* (subpath \"%s\"))\n", expanded))
		}
	}

	sb.WriteString("\n")

	// Deny rules have higher priority (applied after allow)
	// Note: Seatbelt evaluates rules in order, so denies after allows will override
	for _, pattern := range policy.Filesystem.DenyRead {
		expanded, err := util.ExpandVariables(pattern)
		if err != nil {
			return fmt.Errorf("failed to expand pattern %s: %w", pattern, err)
		}

		if util.ContainsGlob(expanded) {
			baseDir := filepath.Dir(strings.TrimSuffix(expanded, "/**"))
			sb.WriteString(fmt.Sprintf("(deny file-read* (subpath \"%s\"))\n", baseDir))
		} else {
			sb.WriteString(fmt.Sprintf("(deny file-read* (subpath \"%s\"))\n", expanded))
		}
	}

	for _, pattern := range policy.Filesystem.DenyWrite {
		expanded, err := util.ExpandVariables(pattern)
		if err != nil {
			return fmt.Errorf("failed to expand pattern %s: %w", pattern, err)
		}

		if util.ContainsGlob(expanded) {
			baseDir := filepath.Dir(strings.TrimSuffix(expanded, "/**"))
			sb.WriteString(fmt.Sprintf("(deny file-write* (subpath \"%s\"))\n", baseDir))
		} else {
			sb.WriteString(fmt.Sprintf("(deny file-write* (subpath \"%s\"))\n", expanded))
		}
	}

	sb.WriteString("\n")

	return nil
}

// translateNetwork translates network access rules.
func (t *policyTranslator) translateNetwork(policy *sandbox.SandboxPolicy, sb *strings.Builder) error {
	sb.WriteString(";; Network access\n")

	// If there are allow outbound rules, allow network-outbound generally
	// (Seatbelt doesn't support fine-grained host:port filtering in all cases)
	// Note: This is a limitation of Seatbelt - for more fine-grained control,
	// consider using a network filtering solution or firewall rules
	if len(policy.Network.AllowOutbound) > 0 {
		sb.WriteString(";; Network outbound allowed to specific hosts\n")
		sb.WriteString(";; Note: Seatbelt has limited host-based filtering, consider using firewall rules for strict control\n")
		sb.WriteString("(allow network-outbound)\n")
	}

	// If deny outbound includes "*:*", block all network
	for _, pattern := range policy.Network.DenyOutbound {
		if pattern == "*:*" {
			sb.WriteString(";; Network outbound denied\n")
			sb.WriteString("(deny network-outbound)\n")
			break
		}
	}

	sb.WriteString("\n")

	return nil
}

// translateProcess translates process execution rules.
func (t *policyTranslator) translateProcess(policy *sandbox.SandboxPolicy, sb *strings.Builder) error {
	sb.WriteString(";; Process execution\n")

	// Add allow exec rules
	for _, exePath := range policy.Process.AllowExec {
		expanded, err := util.ExpandVariables(exePath)
		if err != nil {
			return fmt.Errorf("failed to expand exec path %s: %w", exePath, err)
		}

		if util.ContainsGlob(expanded) {
			// For glob patterns, use subpath to allow anything under that directory
			baseDir := filepath.Dir(strings.TrimSuffix(expanded, "/**"))
			sb.WriteString(fmt.Sprintf("(allow process-exec* (subpath \"%s\"))\n", baseDir))
		} else {
			sb.WriteString(fmt.Sprintf("(allow process-exec* (literal \"%s\"))\n", expanded))
		}
	}

	sb.WriteString("\n")

	// Add deny exec rules
	for _, exePath := range policy.Process.DenyExec {
		expanded, err := util.ExpandVariables(exePath)
		if err != nil {
			return fmt.Errorf("failed to expand exec path %s: %w", exePath, err)
		}

		if util.ContainsGlob(expanded) {
			baseDir := filepath.Dir(strings.TrimSuffix(expanded, "/**"))
			sb.WriteString(fmt.Sprintf("(deny process-exec* (subpath \"%s\"))\n", baseDir))
		} else {
			sb.WriteString(fmt.Sprintf("(deny process-exec* (literal \"%s\"))\n", expanded))
		}
	}

	sb.WriteString("\n")

	return nil
}