package config

import (
	"bytes"
	"fmt"
	"reflect"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/briefing"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/module"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/report"
	"gopkg.in/yaml.v3"
)

func (cfg Config) ReportModuleOverrides() (map[report.ID][]module.ConfigItem, error) {
	overrides := map[report.ID][]module.ConfigItem{}
	seenReports := map[report.ID]string{}
	for key, reportCfg := range cfg.Reports {
		id, err := report.IDForConfigKey(key)
		if err != nil {
			return nil, fmt.Errorf("reports.%s: %w", key, err)
		}
		if previous, ok := seenReports[id]; ok {
			return nil, fmt.Errorf("reports.%s duplicates report override %q", key, previous)
		}
		seenReports[id] = key
		if !reportCfg.deterministicModulesSet {
			continue
		}
		overrides[id] = moduleItemsFromConfig(reportCfg.DeterministicModules)
	}
	return overrides, nil
}

func normalizeReportModules(cfg *Config) error {
	if cfg.Reports == nil {
		cfg.Reports = map[string]ReportConfig{}
	}
	moduleRegistry, err := briefing.DefaultModuleRegistry()
	if err != nil {
		return fmt.Errorf("initialize module registry: %w", err)
	}
	reportRegistry := report.DefaultRegistry()
	seenReports := map[report.ID]string{}
	for key, reportCfg := range cfg.Reports {
		reportID, err := report.IDForConfigKey(key)
		if err != nil {
			return fmt.Errorf("reports.%s: %w", key, err)
		}
		if previous, ok := seenReports[reportID]; ok {
			return fmt.Errorf("reports.%s duplicates report override %q", key, previous)
		}
		seenReports[reportID] = key
		if _, err := reportRegistry.Lookup(reportID); err != nil {
			return fmt.Errorf("reports.%s: %w", key, err)
		}
		if !reportCfg.deterministicModulesSet {
			continue
		}
		for i, rawItem := range reportCfg.DeterministicModules {
			options, err := normalizeModuleOptions(moduleRegistry, rawItem.ID, rawItem.Options)
			if err != nil {
				return fmt.Errorf("reports.%s.deterministic_modules[%d]: %w", key, i, err)
			}
			reportCfg.DeterministicModules[i].Options = options
		}
		items := moduleItemsFromConfig(reportCfg.DeterministicModules)
		if err := moduleRegistry.ValidateComposition(reportID, items); err != nil {
			return fmt.Errorf("reports.%s.deterministic_modules: %w", key, err)
		}
		cfg.Reports[key] = reportCfg
	}
	return nil
}

func validateReportModules(cfg Config) error {
	if cfg.Reports == nil {
		return nil
	}
	moduleRegistry, err := briefing.DefaultModuleRegistry()
	if err != nil {
		return fmt.Errorf("initialize module registry: %w", err)
	}
	reportRegistry := report.DefaultRegistry()
	seenReports := map[report.ID]string{}
	for key, reportCfg := range cfg.Reports {
		reportID, err := report.IDForConfigKey(key)
		if err != nil {
			return fmt.Errorf("reports.%s: %w", key, err)
		}
		if previous, ok := seenReports[reportID]; ok {
			return fmt.Errorf("reports.%s duplicates report override %q", key, previous)
		}
		seenReports[reportID] = key
		if _, err := reportRegistry.Lookup(reportID); err != nil {
			return fmt.Errorf("reports.%s: %w", key, err)
		}
		if !reportCfg.deterministicModulesSet {
			continue
		}
		items := make([]module.ConfigItem, 0, len(reportCfg.DeterministicModules))
		for i, rawItem := range reportCfg.DeterministicModules {
			options := rawItem.Options
			if options != nil {
				normalized, err := normalizeModuleOptions(moduleRegistry, rawItem.ID, options)
				if err != nil {
					return fmt.Errorf("reports.%s.deterministic_modules[%d]: %w", key, i, err)
				}
				options = normalized
			}
			items = append(items, module.ConfigItem{ID: rawItem.ID, Options: options})
		}
		if err := moduleRegistry.ValidateComposition(reportID, items); err != nil {
			return fmt.Errorf("reports.%s.deterministic_modules: %w", key, err)
		}
	}
	return nil
}

func moduleItemsFromConfig(items []ModuleConfigItem) []module.ConfigItem {
	out := make([]module.ConfigItem, 0, len(items))
	for _, item := range items {
		out = append(out, module.ConfigItem{ID: item.ID, Options: item.Options})
	}
	return out
}

func normalizeModuleOptions(registry briefing.ModuleRegistry, id module.ID, raw any) (any, error) {
	if raw == nil {
		return nil, nil
	}
	definition, err := registry.Lookup(id)
	if err != nil {
		return nil, err
	}
	if definition.DefaultOptions == nil {
		return nil, fmt.Errorf("module %q does not accept options", id)
	}
	if err := definition.ValidateOptions(raw); err == nil {
		return raw, nil
	}
	optionType := reflect.TypeOf(definition.DefaultOptions)
	normalized, err := decodeKnownOptions(raw, optionType)
	if err != nil {
		return nil, fmt.Errorf("module %q options are invalid: %w", id, err)
	}
	return normalized, nil
}

func decodeKnownOptions(raw any, optionType reflect.Type) (any, error) {
	data, err := yaml.Marshal(raw)
	if err != nil {
		return nil, err
	}
	target := reflect.New(optionType)
	decoder := yaml.NewDecoder(bytes.NewReader(data))
	decoder.KnownFields(true)
	if err := decoder.Decode(target.Interface()); err != nil {
		return nil, err
	}
	return target.Elem().Interface(), nil
}