package config

import (
	"fmt"
	"os"
	"strconv"
	"strings"

	"gitea.maximumdirect.net/eric/notarius/internal/core/diagnostics"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
)

func LoadFromEnv() (Config, error) {
	cfg := Default()
	if err := cfg.applyEnvOverridesWithLookup(os.LookupEnv); err != nil {
		return Config{}, err
	}
	return cfg, nil
}

func (c *Config) ApplyEnvOverrides() error {
	return c.applyEnvOverridesWithLookup(os.LookupEnv)
}

func (c *Config) ApplyEnvOverridesWithLookup(lookup func(string) (string, bool)) error {
	return c.applyEnvOverridesWithLookup(lookup)
}

func (c *Config) applyEnvOverridesWithLookup(lookup func(string) (string, bool)) error {
	if c == nil {
		return fmt.Errorf("config must not be nil")
	}
	if c.LLMProfiles == nil {
		c.LLMProfiles = map[string]LLMProfile{}
	}

	defaultProfile := c.LLMProfiles[pipeline.DefaultLLMProfile]
	if raw, ok := lookup("NOTARIUS_LLM_DEFAULT_API_KEY"); ok {
		defaultProfile.APIKey = raw
	}
	if raw, ok := lookup("NOTARIUS_LLM_DEFAULT_BASE_URL"); ok {
		defaultProfile.BaseURL = strings.TrimSpace(raw)
	}
	if raw, ok := lookup("NOTARIUS_LLM_DEFAULT_MODEL"); ok {
		defaultProfile.Model = strings.TrimSpace(raw)
	}
	if raw, ok := lookup("NOTARIUS_LLM_DEFAULT_TIMEOUT_SECONDS"); ok {
		value, err := parseIntEnv("NOTARIUS_LLM_DEFAULT_TIMEOUT_SECONDS", raw)
		if err != nil {
			return err
		}
		defaultProfile.TimeoutSeconds = value
	}
	if raw, ok := lookup("NOTARIUS_LLM_DEFAULT_MAX_RETRIES"); ok {
		value, err := parseIntEnv("NOTARIUS_LLM_DEFAULT_MAX_RETRIES", raw)
		if err != nil {
			return err
		}
		defaultProfile.MaxRetries = value
	}
	if raw, ok := lookup("NOTARIUS_LLM_DEFAULT_MAX_CONCURRENCY"); ok {
		value, err := parseIntEnv("NOTARIUS_LLM_DEFAULT_MAX_CONCURRENCY", raw)
		if err != nil {
			return err
		}
		defaultProfile.MaxConcurrency = value
	}
	c.LLMProfiles[pipeline.DefaultLLMProfile] = defaultProfile

	if raw, ok := lookup("NOTARIUS_TOTAL_LLM_CONCURRENCY"); ok {
		value, err := parseIntEnv("NOTARIUS_TOTAL_LLM_CONCURRENCY", raw)
		if err != nil {
			return err
		}
		c.Concurrency.TotalLLM = value
	}
	if raw, ok := lookup("NOTARIUS_WORK_DIR"); ok {
		c.Diagnostics.WorkDir = strings.TrimSpace(raw)
	}
	if raw, ok := lookup("NOTARIUS_DIAGNOSTICS_RETENTION"); ok {
		c.Diagnostics.Retention = diagnostics.RetentionMode(strings.TrimSpace(raw))
	}
	return nil
}

func parseIntEnv(name string, raw string) (int, error) {
	value, err := strconv.Atoi(strings.TrimSpace(raw))
	if err != nil {
		return 0, fmt.Errorf("%s: must be an integer", name)
	}
	return value, nil
}