package spec

import (
	"fmt"
	"strings"

	"github.com/fleetdm/fleet/v4/server/platform/logging"
)

// DeprecatedKeyMapping defines a mapping from an old YAML key path to a new one.
// Paths use dot notation for nested keys, with [] to indicate "all array elements".
// Examples:
//   - "team_settings" -> "settings"
//   - "queries" -> "reports"
//   - "org_settings.mdm.apple_business_manager[].macos_team" -> "org_settings.mdm.apple_business_manager[].macos_fleet"
type DeprecatedKeyMapping struct {
	OldPath string
	NewPath string
}

// DeprecatedGitOpsKeyMappings is the single source of truth for all deprecated key renames.
// It serves two purposes:
//  1. ApplyDeprecatedKeyMappings uses the full paths to migrate deprecated keys in gitops YAML input.
//  2. buildAliasRules (in generate_gitops.go) extracts leaf key names to rename keys in
//     serialized output for generate_gitops, fleetctl get, and fleetctl apply.
//
// When adding new deprecations, add them here.
var DeprecatedGitOpsKeyMappings = []DeprecatedKeyMapping{
	// Top-level gitops keys
	{"team_settings", "settings"},
	{"queries", "reports"},

	// Controls: macos_settings -> apple_settings (parent first, then children)
	{"controls.macos_settings", "controls.apple_settings"},
	{"controls.apple_settings.custom_settings", "controls.apple_settings.configuration_profiles"},

	// Controls: windows_settings children
	{"controls.windows_settings.custom_settings", "controls.windows_settings.configuration_profiles"},

	// Controls: android_settings children
	{"controls.android_settings.custom_settings", "controls.android_settings.configuration_profiles"},

	// Controls: macos_setup -> setup_experience (parent first, then children)
	{"controls.macos_setup", "controls.setup_experience"},
	{"controls.setup_experience.bootstrap_package", "controls.setup_experience.macos_bootstrap_package"},
	{"controls.setup_experience.macos_setup_assistant", "controls.setup_experience.apple_setup_assistant"},
	{"controls.setup_experience.enable_release_device_manually", "controls.setup_experience.apple_enable_release_device_manually"},
	{"controls.setup_experience.script", "controls.setup_experience.macos_script"},
	{"controls.setup_experience.manual_agent_install", "controls.setup_experience.macos_manual_agent_install"},
	{"controls.setup_experience.enable_managed_local_account", "controls.setup_experience.enable_create_local_admin_account"},

	// Org settings: server_settings
	{"org_settings.server_settings.live_query_disabled", "org_settings.server_settings.live_reporting_disabled"},
	{"org_settings.server_settings.query_reports_disabled", "org_settings.server_settings.discard_reports_data"},
	{"org_settings.server_settings.query_report_cap", "org_settings.server_settings.report_cap"},

	// Nested keys in org_settings.mdm.apple_business_manager[]
	{"org_settings.mdm.apple_business_manager[].macos_team", "org_settings.mdm.apple_business_manager[].macos_fleet"},
	{"org_settings.mdm.apple_business_manager[].ios_team", "org_settings.mdm.apple_business_manager[].ios_fleet"},
	{"org_settings.mdm.apple_business_manager[].ipados_team", "org_settings.mdm.apple_business_manager[].ipados_fleet"},

	// Nested keys in org_settings.mdm.volume_purchasing_program[]
	{"org_settings.mdm.volume_purchasing_program[].teams", "org_settings.mdm.volume_purchasing_program[].fleets"},

	// The following entries are renameto tags on struct fields that appear in serialized
	// API output (fleetctl get and fleetctl apply) but are not gitops input keys. They are
	// included here so that buildAliasRules can derive them. The paths are leaf-only (no dots)
	// since they don't participate in ApplyDeprecatedKeyMappings traversal.
	{"available_teams", "available_fleets"},
	{"default_team", "default_fleet"},
	{"host_team_id", "host_fleet_id"},
	{"inherited_query_count", "inherited_report_count"},
	{"ios_team_id", "ios_fleet_id"},
	{"ipados_team_id", "ipados_fleet_id"},
	{"live_query_results", "live_report_results"},
	{"macos_team_id", "macos_fleet_id"},
	{"query_count", "report_count"},
	{"query_id", "report_id"},
	{"query_ids", "report_ids"},
	{"query_name", "report_name"},
	{"query_stats", "report_stats"},
	{"scheduled_query_id", "scheduled_report_id"},
	{"scheduled_query_name", "scheduled_report_name"},
	{"team", "fleet"},
	{"team_id", "fleet_id"},
	{"team_ids_by_name", "fleet_ids_by_name"},
	{"team_ids", "fleet_ids"},
	{"team_name", "fleet_name"},
}

// ApplyDeprecatedKeyMappings walks the YAML data map and migrates deprecated keys to their new names.
// It logs warnings for each deprecated key found and returns an error if both old and new keys are specified.
// After this function returns successfully, only the new key names will be present in the data.
func ApplyDeprecatedKeyMappings(data map[string]any, logFn Logf) error {
	for _, mapping := range DeprecatedGitOpsKeyMappings {
		if err := migrateKeyPath(data, mapping.OldPath, mapping.NewPath, logFn); err != nil {
			return err
		}
	}
	return nil
}

// migrateKeyPath migrates a single deprecated key path to its new path.
// Paths are dot-separated, with [] indicating iteration over array elements.
func migrateKeyPath(data map[string]any, oldPath, newPath string, logFn Logf) error {
	oldParts := strings.Split(oldPath, ".")
	newParts := strings.Split(newPath, ".")

	return migrateKeyPathRecursive(data, oldParts, newParts, oldPath, newPath, logFn)
}

func migrateKeyPathRecursive(data map[string]any, oldParts, newParts []string, fullOldPath, fullNewPath string, logFn Logf) error {
	if len(oldParts) == 0 || len(newParts) == 0 {
		return nil
	}

	oldKey := oldParts[0]
	newKey := newParts[0]

	// Check if this key references an array (e.g. "apple_business_manager[]").
	if trimmed, ok := strings.CutSuffix(oldKey, "[]"); ok {
		oldKey = trimmed
		arr, ok := data[oldKey]
		if !ok {
			return nil // Key doesn't exist, nothing to migrate
		}

		arrSlice, ok := arr.([]any)
		if !ok {
			return nil // Not an array, skip
		}

		// Recurse into each array element with the remaining path parts.
		for i, elem := range arrSlice {
			elemMap, ok := elem.(map[string]any)
			if !ok {
				continue // Not a map, skip
			}

			if err := migrateKeyPathRecursive(elemMap, oldParts[1:], newParts[1:], fullOldPath, fullNewPath, logFn); err != nil {
				return fmt.Errorf("in array element %d: %w", i, err)
			}
		}
		return nil
	}

	// Check if we're at the final key (leaf)
	if len(oldParts) == 1 {
		return migrateLeafKey(data, oldKey, newKey, fullOldPath, fullNewPath, logFn)
	}

	// Recurse into nested map
	nested, ok := data[oldKey]
	if !ok {
		return nil // Key doesn't exist, nothing to migrate
	}

	nestedMap, ok := nested.(map[string]any)
	if !ok {
		return nil // Not a map, skip
	}

	return migrateKeyPathRecursive(nestedMap, oldParts[1:], newParts[1:], fullOldPath, fullNewPath, logFn)
}

// migrateLeafKey handles the actual key migration at the leaf level.
func migrateLeafKey(data map[string]any, oldKey, newKey, fullOldPath, fullNewPath string, logFn Logf) error {
	oldValue, oldExists := data[oldKey]
	_, newExists := data[newKey]

	if !oldExists {
		return nil // Old key doesn't exist, nothing to migrate
	}

	if newExists {
		return fmt.Errorf("cannot specify both '%s' (deprecated) and '%s'; use only '%s'", fullOldPath, fullNewPath, fullNewPath)
	}

	// Log deprecation warning
	if logFn != nil {
		if logging.TopicEnabled(logging.DeprecatedFieldTopic) {
			logFn("[!] '%s' is deprecated; use '%s' instead\n", fullOldPath, fullNewPath)
		}
	}

	// Copy value to new key and remove old key
	data[newKey] = oldValue
	delete(data, oldKey)

	return nil
}