1package config
  2
  3import (
  4	"fmt"
  5	"os"
  6	"path/filepath"
  7
  8	"github.com/spf13/viper"
  9
 10	"llm_aggregator/internal/cli"
 11	"llm_aggregator/internal/defaults"
 12	"llm_aggregator/internal/progress"
 13	"llm_aggregator/internal/runtime"
 14	"llm_aggregator/internal/style"
 15)
 16
 17// Config holds the application configuration loaded from TOML file, environment variables, and CLI arguments.
 18type Config struct {
 19	// Feed aggregation options
 20	MaxArticlesPerFeed int    `mapstructure:"max_articles_per_feed"`
 21	MaxDaysOld         int    `mapstructure:"max_days_old"`
 22	MaxTotalArticles   int    `mapstructure:"max_total_articles"`
 23	IncludeKeywords    string `mapstructure:"include_keywords"`
 24	ExcludeKeywords    string `mapstructure:"exclude_keywords"`
 25
 26	// LLM API options
 27	APIKey      string  `mapstructure:"api_key"`
 28	BaseURL     string  `mapstructure:"base_url"`
 29	Model       string  `mapstructure:"model"`
 30	MaxTokens   int     `mapstructure:"max_tokens"`
 31	Temperature float64 `mapstructure:"temperature"`
 32
 33	// System prompt
 34	SystemPrompt string `mapstructure:"system_prompt"`
 35
 36	// Output options
 37	Output          string `mapstructure:"output"`
 38	OutputFile      string `mapstructure:"output_file"`
 39	IncludeArticles bool   `mapstructure:"include_articles"`
 40}
 41
 42// GetViper returns the global viper instance with all configuration sources set up.
 43// The precedence order is: CLI flags > Environment variables > Config file > Defaults.
 44//
 45// NOTE: Viper uses a singleton pattern. Subsequent calls to GetViper() return the SAME
 46// instance with all previously set values. This means defaults are only set once,
 47// environment vars are bound once, and the config file is read once. Do NOT call this
 48// expecting a fresh state — if you need a fresh instance for testing, use viper.New() directly.
 49func GetViper() *viper.Viper {
 50	// Set defaults first (lowest priority)
 51	setDefaults()
 52	// Initialise or get existing Viper instance
 53	v := viper.GetViper()
 54	// Ensure defaults are set (for fresh instances)
 55	setDefaultsOn(v)
 56	// Set environment variable prefix
 57	v.SetEnvPrefix("LLM_AGGREGATOR")
 58	v.AutomaticEnv()
 59	// Bind environment variables to config fields
 60	bindEnvVars(v)
 61	// Get config path from XDG
 62	configPath, err := GetConfigPath()
 63	if err == nil {
 64		// Set config file path
 65		v.SetConfigFile(configPath)
 66		// Debug: show what config file is being used
 67		// Try to read config file
 68		if err := v.ReadInConfig(); err != nil {
 69			// If config file doesn't exist, that's OK - we'll use defaults + env vars
 70			if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
 71				fmt.Fprintln(os.Stderr, style.Warningf("error reading config file: %v", err))
 72			} else {
 73			}
 74		} else {
 75		}
 76	}
 77	return v
 78}
 79
 80// setDefaults sets default values on the global viper instance.
 81func setDefaults() {
 82	v := viper.GetViper()
 83	setDefaultsOn(v)
 84}
 85
 86// setDefaultsOn sets default values on the given viper instance.
 87func setDefaultsOn(v *viper.Viper) {
 88	// Feed aggregation defaults
 89	v.SetDefault("max_articles_per_feed", defaults.DefaultMaxArticlesPerFeed)
 90	v.SetDefault("max_days_old", defaults.DefaultMaxDaysOld)
 91	v.SetDefault("max_total_articles", defaults.DefaultMaxTotalArticles)
 92	// LLM API defaults
 93	v.SetDefault("base_url", defaults.DefaultBaseURL)
 94	v.SetDefault("model", defaults.DefaultModel)
 95	v.SetDefault("max_tokens", defaults.DefaultMaxTokens)
 96	v.SetDefault("temperature", defaults.DefaultTemperature)
 97	// System prompt default
 98	v.SetDefault("system_prompt", defaults.DefaultSystemPrompt)
 99	// Output defaults
100	v.SetDefault("output", defaults.DefaultOutput)
101	v.SetDefault("include_articles", defaults.DefaultIncludeArticles)
102}
103
104// BindCLIArgs binds CLI argument values to viper with highest precedence.
105// This should be called after parsing CLI arguments to override config file/env defaults.
106func BindCLIArgs(v *viper.Viper, args map[string]any) {
107	for key, value := range args {
108		if value != nil && !isZero(value) {
109			v.Set(key, value)
110		}
111	}
112}
113
114// isZero checks if a value is the zero value for its type.
115//
116// NOTE: This function is critical for CLI argument handling. Pointer types
117// (*string, *int, etc.) return true only when nil (not provided), NOT when
118// pointing to a zero value. This allows distinguishing between "flag not
119// provided" (nil) vs "flag explicitly set to zero" (e.g., --temperature 0
120// should override default, but no flag means preserve default).
121func isZero(v any) bool {
122	// Handle nil interface values first (before type switch)
123	if v == nil {
124		return true
125	}
126	switch val := v.(type) {
127	case string:
128		return val == ""
129	case int:
130		return val == 0
131	case int8:
132		return val == 0
133	case int16:
134		return val == 0
135	case int32:
136		return val == 0
137	case int64:
138		return val == 0
139	case float32:
140		return val == 0.0
141	case float64:
142		return val == 0.0
143	case bool:
144		return !val
145	case *string:
146		return val == nil
147	case *int:
148		return val == nil
149	case *int8:
150		return val == nil
151	case *int16:
152		return val == nil
153	case *int32:
154		return val == nil
155	case *int64:
156		return val == nil
157	case *float32:
158		return val == nil
159	case *float64:
160		return val == nil
161	case *bool:
162		return val == nil
163	default:
164		return false
165	}
166}
167
168// ViperToRuntime converts viper configuration directly to runtime.Runtime.
169func ViperToRuntime(v *viper.Viper, feedsFile, prompt string) *runtime.Runtime {
170	rt := &runtime.Runtime{
171		FeedsFile: feedsFile,
172		Prompt:    prompt,
173		Progress:  &progress.NoopLogger{},
174	}
175	// Feed aggregation options
176	rt.MaxArticlesPerFeed = v.GetInt("max_articles_per_feed")
177	rt.MaxDaysOld = v.GetInt("max_days_old")
178	rt.MaxTotalArticles = v.GetInt("max_total_articles")
179	// Keywords
180	includeKeywords := v.GetString("include_keywords")
181	excludeKeywords := v.GetString("exclude_keywords")
182	if includeKeywords != "" {
183		rt.IncludeKeywords = cli.ParseKeywords(includeKeywords)
184	}
185	if excludeKeywords != "" {
186		rt.ExcludeKeywords = cli.ParseKeywords(excludeKeywords)
187	}
188	// LLM API options
189	rt.APIKey = v.GetString("api_key")
190	rt.BaseURL = v.GetString("base_url")
191	rt.Model = v.GetString("model")
192	rt.MaxTokens = v.GetInt("max_tokens")
193	rt.Temperature = v.GetFloat64("temperature")
194	// System prompt
195	rt.SystemPrompt = v.GetString("system_prompt")
196	// Output options
197	rt.Output = v.GetString("output")
198	rt.OutputFile = v.GetString("output_file")
199	rt.IncludeArticles = v.GetBool("include_articles")
200	return rt
201}
202
203// bindEnvVars binds environment variables to viper keys.
204func bindEnvVars(v *viper.Viper) {
205	// Feed aggregation options
206	v.BindEnv("max_articles_per_feed", "LLM_AGGREGATOR_MAX_ARTICLES_PER_FEED")
207	v.BindEnv("max_days_old", "LLM_AGGREGATOR_MAX_DAYS_OLD")
208	v.BindEnv("max_total_articles", "LLM_AGGREGATOR_MAX_TOTAL_ARTICLES")
209	v.BindEnv("include_keywords", "LLM_AGGREGATOR_INCLUDE_KEYWORDS")
210	v.BindEnv("exclude_keywords", "LLM_AGGREGATOR_EXCLUDE_KEYWORDS")
211	// LLM API options
212	v.BindEnv("api_key", "LLM_AGGREGATOR_API_KEY")
213	v.BindEnv("base_url", "LLM_AGGREGATOR_BASE_URL")
214	v.BindEnv("model", "LLM_AGGREGATOR_MODEL")
215	v.BindEnv("max_tokens", "LLM_AGGREGATOR_MAX_TOKENS")
216	v.BindEnv("temperature", "LLM_AGGREGATOR_TEMPERATURE")
217	// System prompt
218	v.BindEnv("system_prompt", "LLM_AGGREGATOR_SYSTEM_PROMPT")
219	// Output options
220	v.BindEnv("output", "LLM_AGGREGATOR_OUTPUT")
221	v.BindEnv("output_file", "LLM_AGGREGATOR_OUTPUT_FILE")
222	v.BindEnv("include_articles", "LLM_AGGREGATOR_INCLUDE_ARTICLES")
223}
224
225// GetConfigPath returns the path to the config file.
226func GetConfigPath() (string, error) {
227	configDir, err := os.UserConfigDir()
228	if err != nil {
229		return "", fmt.Errorf("failed to get user config directory: %w", err)
230	}
231	return filepath.Join(configDir, "llm_aggregator", "config.toml"), nil
232}