// Package servicedef handles parsing and writing TOML service definition files.
package servicedef

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

	toml "github.com/pelletier/go-toml/v2"

	mcpv1 "git.wntrmute.dev/kyle/mcp/gen/mcp/v1"
)

// ServiceDef is the top-level TOML structure for a service definition file.
type ServiceDef struct {
	Name       string         `toml:"name"`
	Node       string         `toml:"node"`
	Active     *bool          `toml:"active,omitempty"`
	Components []ComponentDef `toml:"components"`
}

// ComponentDef describes a single container component within a service.
type ComponentDef struct {
	Name    string   `toml:"name"`
	Image   string   `toml:"image"`
	Network string   `toml:"network,omitempty"`
	User    string   `toml:"user,omitempty"`
	Restart string   `toml:"restart,omitempty"`
	Ports   []string `toml:"ports,omitempty"`
	Volumes []string `toml:"volumes,omitempty"`
	Cmd     []string `toml:"cmd,omitempty"`
}

// Load reads and parses a TOML service definition file. If the active field
// is omitted, it defaults to true.
func Load(path string) (*ServiceDef, error) {
	data, err := os.ReadFile(path) //nolint:gosec // path from trusted config dir
	if err != nil {
		return nil, fmt.Errorf("read service def %q: %w", path, err)
	}

	var def ServiceDef
	if err := toml.Unmarshal(data, &def); err != nil {
		return nil, fmt.Errorf("parse service def %q: %w", path, err)
	}

	if err := validate(&def); err != nil {
		return nil, fmt.Errorf("validate service def %q: %w", path, err)
	}

	if def.Active == nil {
		t := true
		def.Active = &t
	}

	return &def, nil
}

// Write serializes a ServiceDef to TOML and writes it to the given path
// with 0644 permissions. Parent directories are created if needed.
func Write(path string, def *ServiceDef) error {
	if err := os.MkdirAll(filepath.Dir(path), 0o750); err != nil { //nolint:gosec // service defs are non-secret
		return fmt.Errorf("create parent dirs for %q: %w", path, err)
	}

	data, err := toml.Marshal(def)
	if err != nil {
		return fmt.Errorf("marshal service def: %w", err)
	}

	if err := os.WriteFile(path, data, 0o644); err != nil { //nolint:gosec // service defs are non-secret
		return fmt.Errorf("write service def %q: %w", path, err)
	}

	return nil
}

// LoadAll reads all .toml files from dir, parses each one, and returns the
// list sorted by service name.
func LoadAll(dir string) ([]*ServiceDef, error) {
	entries, err := os.ReadDir(dir)
	if err != nil {
		return nil, fmt.Errorf("read service dir %q: %w", dir, err)
	}

	var defs []*ServiceDef
	for _, e := range entries {
		if e.IsDir() || !strings.HasSuffix(e.Name(), ".toml") {
			continue
		}
		def, err := Load(filepath.Join(dir, e.Name()))
		if err != nil {
			return nil, err
		}
		defs = append(defs, def)
	}

	sort.Slice(defs, func(i, j int) bool {
		return defs[i].Name < defs[j].Name
	})

	return defs, nil
}

// validate checks that a ServiceDef has all required fields and that
// component names are unique.
func validate(def *ServiceDef) error {
	if def.Name == "" {
		return fmt.Errorf("service name is required")
	}
	if def.Node == "" {
		return fmt.Errorf("service node is required")
	}
	if len(def.Components) == 0 {
		return fmt.Errorf("service %q must have at least one component", def.Name)
	}

	seen := make(map[string]bool)
	for _, c := range def.Components {
		if c.Name == "" {
			return fmt.Errorf("component name is required in service %q", def.Name)
		}
		if c.Image == "" {
			return fmt.Errorf("component %q image is required in service %q", c.Name, def.Name)
		}
		if seen[c.Name] {
			return fmt.Errorf("duplicate component name %q in service %q", c.Name, def.Name)
		}
		seen[c.Name] = true
	}

	return nil
}

// ToProto converts a ServiceDef to a proto ServiceSpec.
func ToProto(def *ServiceDef) *mcpv1.ServiceSpec {
	spec := &mcpv1.ServiceSpec{
		Name:   def.Name,
		Active: def.Active != nil && *def.Active,
	}

	for _, c := range def.Components {
		spec.Components = append(spec.Components, &mcpv1.ComponentSpec{
			Name:    c.Name,
			Image:   c.Image,
			Network: c.Network,
			User:    c.User,
			Restart: c.Restart,
			Ports:   c.Ports,
			Volumes: c.Volumes,
			Cmd:     c.Cmd,
		})
	}

	return spec
}

// FromProto converts a proto ServiceSpec back to a ServiceDef. The node
// parameter is required because ServiceSpec does not include the node field
// (it is a CLI-side routing concern).
func FromProto(spec *mcpv1.ServiceSpec, node string) *ServiceDef {
	active := spec.GetActive()
	def := &ServiceDef{
		Name:   spec.GetName(),
		Node:   node,
		Active: &active,
	}

	for _, c := range spec.GetComponents() {
		def.Components = append(def.Components, ComponentDef{
			Name:    c.GetName(),
			Image:   c.GetImage(),
			Network: c.GetNetwork(),
			User:    c.GetUser(),
			Restart: c.GetRestart(),
			Ports:   c.GetPorts(),
			Volumes: c.GetVolumes(),
			Cmd:     c.GetCmd(),
		})
	}

	return def
}