// Package config resolves and validates gitflow settings from CLI flags,
// environment variables, and an optional YAML configuration file.
//
// Precedence (highest first): flags, environment variables, config file,
// built-in defaults.
package config

import (
	"errors"
	"fmt"
	"os"
	"strings"
	"time"

	"github.com/spf13/pflag"
	"github.com/spf13/viper"
	"gopkg.in/yaml.v3"

	"gitea.oblak.solutions/dimitar/gitFlow/internal/rules"
)

// AIConfig holds AI agent settings.
type AIConfig struct {
	Enabled   bool   `yaml:"enabled"`
	Provider  string `yaml:"provider"`    // openai, ollama, or anthropic
	Model     string `yaml:"model"`       // model name; empty lets the provider choose
	APIKeyEnv string `yaml:"api_key_env"` // env var holding the API key
	BaseURL   string `yaml:"base_url"`    // provider endpoint override
	Execute   bool   `yaml:"execute"`     // run confirmed AI-suggested commands (experimental)
}

// Config is the fully resolved runtime configuration.
type Config struct {
	Dir        string        `yaml:"dir"`
	Interval   time.Duration `yaml:"interval"`
	Format     string        `yaml:"format"`
	Color      string        `yaml:"color"`
	Theme      string        `yaml:"theme"`
	Notify     bool          `yaml:"notify"`
	Exclude    []string      `yaml:"exclude,omitempty"`
	MaxDepth   int           `yaml:"max_depth"`
	Workers    int           `yaml:"workers"`
	Rules      []rules.Rule  `yaml:"rules,omitempty"`
	AI         AIConfig      `yaml:"ai"`
	ConfigFile string        `yaml:"-"` // path of the loaded config file, if any
}

// flagKeys maps CLI flag names to their viper keys.
var flagKeys = []struct{ flag, key string }{
	{"dir", "dir"},
	{"interval", "interval"},
	{"format", "format"},
	{"color", "color"},
	{"exclude", "exclude"},
	{"max-depth", "max_depth"},
	{"workers", "workers"},
	{"notify", "notify"},
	{"theme", "theme"},
	{"ai", "ai.enabled"},
	{"ai-provider", "ai.provider"},
	{"ai-model", "ai.model"},
	{"ai-execute", "ai.execute"},
}

// RegisterFlags defines every gitflow flag on f. Call Load with the same
// FlagSet to resolve the effective configuration.
func RegisterFlags(f *pflag.FlagSet) {
	f.StringP("dir", "d", ".", "parent directory to scan")
	f.DurationP("interval", "i", 0, "rescan interval (e.g. 30s, 5m); 0 runs once")
	f.StringP("format", "f", "table", "output format: table, json, or compact")
	f.String("color", "auto", "color output: auto, always, or never")
	f.StringSlice("exclude", nil, "glob patterns of directories to skip (repeatable)")
	f.Int("max-depth", 0, "maximum directory depth to scan (0 = unlimited)")
	f.Int("workers", 8, "number of concurrent git scans")
	f.Bool("notify", false, "send desktop notifications when watch sees changes")
	f.String("theme", "dark", "color theme: dark or light")
	f.Bool("ai", false, "enable AI suggestions")
	f.String("ai-provider", "openai", "AI provider: openai, ollama, or anthropic")
	f.String("ai-model", "gpt-4o", "AI model name")
	f.Bool("ai-execute", false, "run confirmed AI-suggested commands (experimental)")
}

// NewFlagSet returns a FlagSet with every gitflow flag registered.
func NewFlagSet() *pflag.FlagSet {
	fs := pflag.NewFlagSet("gitflow", pflag.ContinueOnError)
	RegisterFlags(fs)
	return fs
}

// Load resolves the effective configuration from flags, environment, and
// config file, then validates it.
func Load(flags *pflag.FlagSet) (*Config, error) {
	v := viper.New()
	applyDefaults(v)
	v.SetEnvPrefix("GITFLOW")
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	v.AutomaticEnv()

	if err := readConfigFile(v); err != nil {
		return nil, err
	}
	bindFlags(v, flags)

	cfg := &Config{
		Dir:        v.GetString("dir"),
		Interval:   v.GetDuration("interval"),
		Format:     v.GetString("format"),
		Color:      v.GetString("color"),
		Theme:      v.GetString("theme"),
		Notify:     v.GetBool("notify"),
		Exclude:    v.GetStringSlice("exclude"),
		MaxDepth:   v.GetInt("max_depth"),
		Workers:    v.GetInt("workers"),
		ConfigFile: v.ConfigFileUsed(),
		AI: AIConfig{
			Enabled:   v.GetBool("ai.enabled"),
			Provider:  v.GetString("ai.provider"),
			Model:     v.GetString("ai.model"),
			APIKeyEnv: v.GetString("ai.api_key_env"),
			BaseURL:   v.GetString("ai.base_url"),
			Execute:   v.GetBool("ai.execute"),
		},
	}
	if err := cfg.Validate(); err != nil {
		return nil, err
	}
	// Rules are not exposed as flags; read them from the file/env only.
	var rulesList []rules.Rule
	if err := v.UnmarshalKey("rules", &rulesList); err != nil {
		return nil, fmt.Errorf("config: rules: %w", err)
	}
	cfg.Rules = rulesList
	for _, r := range cfg.Rules {
		if err := r.Validate(); err != nil {
			return nil, err
		}
	}
	return cfg, nil
}

func applyDefaults(v *viper.Viper) {
	v.SetDefault("dir", ".")
	v.SetDefault("interval", 0)
	v.SetDefault("format", "table")
	v.SetDefault("color", "auto")
	v.SetDefault("exclude", []string{})
	v.SetDefault("max_depth", 0)
	v.SetDefault("workers", 8)
	v.SetDefault("notify", false)
	v.SetDefault("theme", "dark")
	v.SetDefault("ai.enabled", false)
	v.SetDefault("ai.provider", "openai")
	v.SetDefault("ai.model", "gpt-4o")
	v.SetDefault("ai.api_key_env", "OPENAI_API_KEY")
	v.SetDefault("ai.base_url", "")
	v.SetDefault("ai.execute", false)
}

// readConfigFile loads ~/.gitflow.yaml (or $GITFLOW_CONFIG when set). A
// missing config file is not an error; a malformed one is.
func readConfigFile(v *viper.Viper) error {
	if path := os.Getenv("GITFLOW_CONFIG"); path != "" {
		v.SetConfigFile(path)
	} else {
		v.SetConfigName(".gitflow")
		v.SetConfigType("yaml")
		v.AddConfigPath("$HOME")
		v.AddConfigPath(".")
	}
	if err := v.ReadInConfig(); err != nil {
		var notFound viper.ConfigFileNotFoundError
		if errors.As(err, &notFound) {
			return nil
		}
		return fmt.Errorf("config: %w", err)
	}
	return nil
}

func bindFlags(v *viper.Viper, flags *pflag.FlagSet) {
	for _, fk := range flagKeys {
		if fl := flags.Lookup(fk.flag); fl != nil {
			_ = v.BindPFlag(fk.key, fl)
		}
	}
}

// Validate rejects configuration that cannot be used.
func (c *Config) Validate() error {
	if c.Dir == "" {
		return errors.New("config: dir must not be empty")
	}
	switch c.Format {
	case "table", "json", "compact":
	default:
		return fmt.Errorf("config: unsupported format %q (want table, json, or compact)", c.Format)
	}
	switch c.Color {
	case "auto", "always", "never":
	default:
		return fmt.Errorf("config: unsupported color mode %q (want auto, always, or never)", c.Color)
	}
	switch c.Theme {
	case "dark", "light":
	default:
		return fmt.Errorf("config: unsupported theme %q (want dark or light)", c.Theme)
	}
	if c.Interval < 0 {
		return errors.New("config: interval must not be negative")
	}
	if c.MaxDepth < 0 {
		return errors.New("config: max-depth must not be negative")
	}
	if c.Workers < 1 {
		return errors.New("config: workers must be at least 1")
	}
	if c.AI.Enabled {
		switch c.AI.Provider {
		case "openai", "ollama", "anthropic":
		default:
			return fmt.Errorf("config: unsupported ai provider %q (want openai, ollama, or anthropic)", c.AI.Provider)
		}
	}
	return nil
}

// Dump renders the effective configuration as human-readable YAML, with the
// interval shown as a duration string.
func (c *Config) Dump() (string, error) {
	v := map[string]any{
		"config_file": c.ConfigFile,
		"dir":         c.Dir,
		"interval":    c.Interval.String(),
		"format":      c.Format,
		"color":       c.Color,
		"exclude":     c.Exclude,
		"max_depth":   c.MaxDepth,
		"workers":     c.Workers,
		"notify":      c.Notify,
		"theme":       c.Theme,
		"rules":       c.Rules,
		"ai": map[string]any{
			"enabled":     c.AI.Enabled,
			"provider":    c.AI.Provider,
			"model":       c.AI.Model,
			"api_key_env": c.AI.APIKeyEnv,
			"base_url":    c.AI.BaseURL,
			"execute":     c.AI.Execute,
		},
	}
	out, err := yaml.Marshal(v)
	if err != nil {
		return "", err
	}
	return string(out), nil
}