package config

import (
	"errors"
	"net/netip"
	"os"

	"github.com/Pingu-Studio/MaidnCLI/internal/talos"
	"gopkg.in/yaml.v3"
)

func Load(path string) (Config, error) {
	var cfg Config
	data, err := os.ReadFile(path)
	if err != nil {
		return cfg, err
	}
	if err := yaml.Unmarshal(data, &cfg); err != nil {
		return cfg, err
	}
	applyDefaults(&cfg)
	return cfg, Validate(cfg)
}

func Save(path string, cfg Config) error {
	applyDefaults(&cfg)
	if err := Validate(cfg); err != nil {
		return err
	}
	data, err := yaml.Marshal(cfg)
	if err != nil {
		return err
	}
	return os.WriteFile(path, data, 0644)
}

func applyDefaults(cfg *Config) {
	if cfg.Git.Provider == "" {
		cfg.Git.Provider = "forgejo"
	}
	if cfg.Git.BaseURL == "" {
		cfg.Git.BaseURL = "https://git.pingu.pw"
	}
	if cfg.Git.CloneParent == "" {
		cfg.Git.CloneParent = cfg.WorkspaceDir
	}
	if cfg.Flux.Branch == "" {
		cfg.Flux.Branch = "main"
	}
	if cfg.Flux.ClusterPath == "" {
		cfg.Flux.ClusterPath = "./clusters/maidn-cd-0"
	}
	if cfg.Flux.ManifestsRepo == "" {
		cfg.Flux.ManifestsRepo = "cicd-deployment-manifests"
	}
	if cfg.Templates.TalosRepoURL == "" {
		cfg.Templates.TalosRepoURL = "https://git.pingu.pw/Maidn/maidn-talos-proxmox.git"
	}
	if cfg.Templates.TalosRepoRef == "" {
		cfg.Templates.TalosRepoRef = "main"
	}
	if cfg.Templates.CICDRepoURL == "" {
		cfg.Templates.CICDRepoURL = "https://git.pingu.pw/Maidn/maidn-cicd-cluster-template.git"
	}
	if cfg.Templates.CICDRepoRef == "" {
		cfg.Templates.CICDRepoRef = "main"
	}
	if cfg.Cilium.TrafficInterface == "" {
		cfg.Cilium.TrafficInterface = "eth1"
	}
	if cfg.Talos.RepoDirName == "" {
		cfg.Talos.RepoDirName = "maidn-talos-proxmox"
	}
	if cfg.Talos.TerraformDir == "" {
		cfg.Talos.TerraformDir = "terraform"
	}
	if cfg.Talos.GeneratedDir == "" {
		cfg.Talos.GeneratedDir = "generated"
	}
	if cfg.Talos.ConfigFileName == "" {
		cfg.Talos.ConfigFileName = "terraform.tfvars"
	}
	if cfg.Talos.Image.UpdateMode == "" {
		cfg.Talos.Image.UpdateMode = "download"
	}
	if cfg.Talos.Image.Storage == "" {
		cfg.Talos.Image.Storage = "local"
	}
	if cfg.Talos.Image.Architecture == "" {
		cfg.Talos.Image.Architecture = "amd64"
	}
	if cfg.Talos.BootstrapEndpoint == "" {
		cfg.Talos.BootstrapEndpoint = cfg.Talos.BootstrapNode
	}
	if cfg.Talos.KubeconfigEndpoint == "" {
		cfg.Talos.KubeconfigEndpoint = cfg.Talos.KubeconfigNode
	}
}

func Validate(cfg Config) error {
	if cfg.WorkspaceDir == "" {
		return errors.New("workspaceDir is required")
	}
	if cfg.Git.BaseURL == "" || cfg.Git.Username == "" || cfg.Git.Owner == "" {
		return errors.New("git baseUrl, username, and owner are required")
	}
	if cfg.Flux.RepoName == "" || cfg.Flux.ClusterPath == "" || cfg.Flux.ManifestsRepo == "" {
		return errors.New("flux repoName, manifestsRepo, and clusterPath are required")
	}
	if cfg.Templates.TalosRepoURL == "" || cfg.Talos.RepoDirName == "" {
		return errors.New("talos template repo and checkout dir are required")
	}
	if cfg.Talos.TerraformDir == "" || cfg.Talos.GeneratedDir == "" || cfg.Talos.ConfigFileName == "" {
		return errors.New("talos terraformDir, generatedDir, and configFileName are required")
	}
	if cfg.Talos.Proxmox.APIURL == "" || cfg.Talos.Proxmox.APITokenID == "" || cfg.Talos.Proxmox.APITokenSecret == "" {
		return errors.New("talos proxmox apiUrl, apiTokenId, and apiTokenSecret are required")
	}
	if cfg.Talos.Cluster.Name == "" || cfg.Talos.Cluster.Domain == "" {
		return errors.New("talos cluster name and domain are required")
	}
	if cfg.Talos.Image.TalosVersion == "" || cfg.Talos.Image.SchematicID == "" {
		return errors.New("talos version and schematicId are required")
	}
	if err := talos.RequireCLICompatibility(cfg.Talos.Image.TalosVersion); err != nil {
		return err
	}
	if cfg.Talos.Image.UpdateMode != "manual" && cfg.Talos.Image.UpdateMode != "download" {
		return errors.New("talos image updateMode must be manual or download")
	}
	if len(cfg.Talos.Nodes) == 0 {
		return errors.New("at least one talos node is required")
	}
	if cfg.Cilium.LoadBalancerStart == "" || cfg.Cilium.LoadBalancerEnd == "" {
		return errors.New("cilium loadBalancerStart and loadBalancerEnd are required")
	}
	start, err := netip.ParseAddr(cfg.Cilium.LoadBalancerStart)
	if err != nil {
		return errors.New("cilium loadBalancerStart must be an IP address")
	}
	end, err := netip.ParseAddr(cfg.Cilium.LoadBalancerEnd)
	if err != nil || start.BitLen() != end.BitLen() || start.Compare(end) > 0 {
		return errors.New("cilium loadBalancerEnd must be an IP address after loadBalancerStart")
	}
	for _, node := range cfg.Talos.Nodes {
		if len(node.Networks) < 2 {
			return errors.New("cilium requires a second static traffic network on every talos node")
		}
		traffic := node.Networks[1]
		prefix, err := netip.ParsePrefix(traffic.CIDR)
		if err != nil || traffic.IP == "" || traffic.Gateway != "" {
			return errors.New("cilium traffic networks require a static IP, valid CIDR, and no gateway")
		}
		nodeIP, err := netip.ParseAddr(traffic.IP)
		if err != nil || !prefix.Contains(nodeIP) || nodeIP == start || nodeIP == end {
			return errors.New("cilium traffic node IP must belong to its CIDR and not use the LoadBalancer range")
		}
		if !prefix.Contains(start) || !prefix.Contains(end) {
			return errors.New("cilium LoadBalancer range must belong to every node traffic network")
		}
	}
	return nil
}