package service

import (
	"encoding/json"
	"errors"
	"os"
	"os/user"
	"path/filepath"
	"slices"
)

type fileConfig struct {
	path        string
	User        string       `json:"user"`
	UserAliases []*Alias     `json:"aliases"`
	Serve       ServerConfig `json:"serve"`
	Remote      ServerConfig `json:"remote"`
	OIDC        OIDCConfig   `json:"oidc"`
}

var defaultAliases = []*Alias{
	{Name: "mine", Command: "list --assignee $me --type issue --status open", Description: "Show open issues assigned to you"},
	{Name: "due", Command: "list --type issue --status open", Description: "Show open issues"},
	{Name: "inbox", Command: "list --mention $me", Description: "Show your inbox"},
}

func LoadConfigFile() (Config, error) {
	path, err := findConfigPath()
	if err != nil {
		return nil, err
	}
	return loadConfig(path)
}

func loadConfig(path string) (*fileConfig, error) {
	fc := &fileConfig{path: path, UserAliases: []*Alias{}}
	data, err := os.ReadFile(path)
	if err != nil {
		if !os.IsNotExist(err) {
			return nil, err
		}
	} else {
		if err := json.Unmarshal(data, fc); err != nil {
			return nil, err
		}
	}
	return fc, nil
}

func findConfigPath() (string, error) {
	dir, err := filepath.Abs(".")
	if err != nil {
		return "", err
	}
	for {
		p := filepath.Join(dir, ".axconfig")
		if _, err := os.Stat(p); err == nil {
			return p, nil
		}
		if parent := filepath.Dir(dir); parent == dir {
			break
		} else {
			dir = parent
		}
	}
	home, err := os.UserHomeDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(home, ".config", "ax", "config.json"), nil
}

func (c *fileConfig) GetUser() string {
	if c.User != "" {
		return c.User
	}
	if u := os.Getenv("AX_USER"); u != "" {
		return u
	}
	if u, err := user.Current(); err == nil {
		return u.Username
	}
	return "unknown"
}

func (c *fileConfig) SetUser(username string) error {
	c.User = username
	return c.Save()
}

func (c *fileConfig) GetAlias(name string) (*Alias, error) {
	for _, a := range c.UserAliases {
		if a.Name == name {
			return a, nil
		}
	}
	for _, a := range defaultAliases {
		if a.Name == name {
			return a, nil
		}
	}
	return nil, errors.New("alias not found")
}

func (c *fileConfig) SetAlias(alias *Alias) error {
	for i, a := range c.UserAliases {
		if a.Name == alias.Name {
			c.UserAliases[i] = alias
			return c.Save()
		}
	}
	c.UserAliases = append(c.UserAliases, alias)
	return c.Save()
}

func (c *fileConfig) DeleteAlias(name string) error {
	for i, a := range c.UserAliases {
		if a.Name == name {
			c.UserAliases = slices.Delete(c.UserAliases, i, i+1)
			return c.Save()
		}
	}
	for _, a := range defaultAliases {
		if a.Name == name {
			return errors.New("cannot delete default alias")
		}
	}
	return errors.New("alias not found")
}

func (c *fileConfig) ListAliases() ([]*Alias, error) {
	seen := make(map[string]bool)
	var result []*Alias
	for _, a := range c.UserAliases {
		result = append(result, a)
		seen[a.Name] = true
	}
	for _, a := range defaultAliases {
		if !seen[a.Name] {
			result = append(result, a)
		}
	}
	return result, nil
}

func (c *fileConfig) GetOIDCConfig() (OIDCConfig, bool) {
	if c.OIDC.Issuer == "" {
		return OIDCConfig{}, false
	}
	cfg := c.OIDC
	if cfg.UserClaim == "" {
		cfg.UserClaim = "preferred_username"
	}
	return cfg, true
}

func (c *fileConfig) GetRemoteConfig() (ServerConfig, bool) {
	if c.Remote.Host == "" {
		return ServerConfig{}, false
	}
	port := c.Remote.Port
	if port == 0 {
		port = 7000
	}
	return ServerConfig{Host: c.Remote.Host, Port: port}, true
}

func (c *fileConfig) GetServerConfig() ServerConfig {
	host := c.Serve.Host
	if host == "" {
		host = "localhost"
	}
	port := c.Serve.Port
	if port == 0 {
		port = 7000
	}
	return ServerConfig{Host: host, Port: port}
}

func (c *fileConfig) Save() error {
	if err := os.MkdirAll(filepath.Dir(c.path), 0755); err != nil {
		return err
	}
	data, err := json.MarshalIndent(c, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(c.path, data, 0644)
}