package config

import (
	"fmt"
	"os"

	"gopkg.in/yaml.v3"
)

type inventoryFragment struct {
	SSHUser         *string            `yaml:"ssh_user"`
	SSHPort         *int               `yaml:"ssh_port"`
	SSHConfigFile   *string            `yaml:"ssh_config_file"`
	SSHIdentityFile *string            `yaml:"ssh_identity_file"`
	SSHNodeHosts    *map[string]string `yaml:"ssh_node_hosts"`
	SSHNodeUsers    *map[string]string `yaml:"ssh_node_users"`
	SSHManagedNodes *[]string          `yaml:"ssh_managed_nodes"`
	ControlPlanes   *[]string          `yaml:"control_planes"`
	Workers         *[]string          `yaml:"workers"`
	Startup         *struct {
		RequiredNodeLabels     *map[string]map[string]string `yaml:"required_node_labels"`
		RequiredNodeLabelsMode *string                       `yaml:"required_node_labels_mode"`
		IgnoreUnavailableNodes *[]string                     `yaml:"ignore_unavailable_nodes"`
	} `yaml:"startup"`
}

// Load runs one orchestration or CLI step.
// Signature: Load(path string) (Config, error).
// Why: keeps behavior explicit so startup/shutdown workflows remain maintainable as services evolve.
func Load(path string) (Config, error) {
	return LoadWithFragments(path)
}

// LoadWithFragments runs one orchestration or CLI step.
// Signature: LoadWithFragments(path string, fragments ...string) (Config, error).
// Why: Terraform can generate a narrow inventory fragment while Ananke keeps
// loading the ordinary host runtime config for imperative recovery behavior.
func LoadWithFragments(path string, fragments ...string) (Config, error) {
	cfg := defaults()

	b, err := os.ReadFile(path)
	if err != nil {
		return Config{}, fmt.Errorf("read config %s: %w", path, err)
	}
	startupProbeRepairConfigured, err := yamlPathExists(b, "startup", "critical_service_startup_probe_repair")
	if err != nil {
		return Config{}, fmt.Errorf("decode config %s: %w", path, err)
	}
	if err := yaml.Unmarshal(b, &cfg); err != nil {
		return Config{}, fmt.Errorf("decode config %s: %w", path, err)
	}
	for _, fragment := range fragments {
		fb, err := os.ReadFile(fragment)
		if err != nil {
			return Config{}, fmt.Errorf("read config fragment %s: %w", fragment, err)
		}
		if err := applyInventoryFragment(fb, &cfg); err != nil {
			return Config{}, fmt.Errorf("decode config fragment %s: %w", fragment, err)
		}
	}

	cfg.applyDefaults()
	if !startupProbeRepairConfigured {
		cfg.Startup.CriticalServiceStartupProbeRepair = defaults().Startup.CriticalServiceStartupProbeRepair
	}
	if err := cfg.Validate(); err != nil {
		return Config{}, err
	}
	return cfg, nil
}

// applyInventoryFragment runs one orchestration or CLI step.
// Signature: applyInventoryFragment(raw []byte, cfg *Config) error.
// Why: restricts generated Terraform fragments to declarative inventory fields
// so they cannot accidentally take over Ananke's recovery behavior.
func applyInventoryFragment(raw []byte, cfg *Config) error {
	var fragment inventoryFragment
	if err := yaml.Unmarshal(raw, &fragment); err != nil {
		return err
	}
	if fragment.SSHUser != nil {
		cfg.SSHUser = *fragment.SSHUser
	}
	if fragment.SSHPort != nil {
		cfg.SSHPort = *fragment.SSHPort
	}
	if fragment.SSHConfigFile != nil {
		cfg.SSHConfigFile = *fragment.SSHConfigFile
	}
	if fragment.SSHIdentityFile != nil {
		cfg.SSHIdentityFile = *fragment.SSHIdentityFile
	}
	if fragment.SSHNodeHosts != nil {
		cfg.SSHNodeHosts = *fragment.SSHNodeHosts
	}
	if fragment.SSHNodeUsers != nil {
		cfg.SSHNodeUsers = *fragment.SSHNodeUsers
	}
	if fragment.SSHManagedNodes != nil {
		cfg.SSHManagedNodes = *fragment.SSHManagedNodes
	}
	if fragment.ControlPlanes != nil {
		cfg.ControlPlanes = *fragment.ControlPlanes
	}
	if fragment.Workers != nil {
		cfg.Workers = *fragment.Workers
	}
	if fragment.Startup == nil {
		return nil
	}
	if fragment.Startup.RequiredNodeLabels != nil {
		cfg.Startup.RequiredNodeLabels = *fragment.Startup.RequiredNodeLabels
	}
	if fragment.Startup.RequiredNodeLabelsMode != nil {
		cfg.Startup.RequiredNodeLabelsMode = *fragment.Startup.RequiredNodeLabelsMode
	}
	if fragment.Startup.IgnoreUnavailableNodes != nil {
		cfg.Startup.IgnoreUnavailableNodes = *fragment.Startup.IgnoreUnavailableNodes
	}
	return nil
}

// yamlPathExists runs one orchestration or CLI step.
// Signature: yamlPathExists(raw []byte, path ...string) (bool, error).
// Why: selected boolean defaults need to distinguish an omitted YAML key from an
// explicit false value after nested startup mappings are decoded.
func yamlPathExists(raw []byte, path ...string) (bool, error) {
	var root yaml.Node
	if err := yaml.Unmarshal(raw, &root); err != nil {
		return false, err
	}
	node := &root
	if node.Kind == yaml.DocumentNode && len(node.Content) > 0 {
		node = node.Content[0]
	}
	for _, key := range path {
		if node.Kind != yaml.MappingNode {
			return false, nil
		}
		found := false
		for i := 0; i+1 < len(node.Content); i += 2 {
			if node.Content[i].Value == key {
				node = node.Content[i+1]
				found = true
				break
			}
		}
		if !found {
			return false, nil
		}
	}
	return true, nil
}