package config

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"gitea.maximumdirect.net/eric/notarius/internal/core/diagnostics"
	"gitea.maximumdirect.net/eric/notarius/internal/framework/pipeline"
	"gopkg.in/yaml.v3"
)

type FileConfig struct {
	Version     int                            `yaml:"version"`
	Scriptorium *FileScriptoriumConfig         `yaml:"scriptorium,omitempty"`
	Pipelines   map[string]FilePipelineProfile `yaml:"pipelines,omitempty"`
	Concurrency *FileConcurrencyConfig         `yaml:"concurrency,omitempty"`
	Diagnostics *FileDiagnosticsConfig         `yaml:"diagnostics,omitempty"`
	Workspace   *FileWorkspaceConfig           `yaml:"workspace,omitempty"`
}

type FileScriptoriumConfig struct {
	ProfileDir  *string `yaml:"profile_dir,omitempty"`
	ProfileFile *string `yaml:"profile_file,omitempty"`
}

type FilePipelineProfile struct {
	Input      fileModuleBinding                  `yaml:"input"`
	Chunk      *fileModuleBinding                 `yaml:"chunk,omitempty"`
	Artifacts  map[string]FileArtifactLaneProfile `yaml:"artifacts,omitempty"`
	Output     *fileModuleBinding                 `yaml:"output,omitempty"`
	References map[string]string                  `yaml:"references,omitempty"`
}

type FileArtifactLaneProfile struct {
	Extract    fileModuleBinding   `yaml:"extract"`
	Merge      *fileModuleBinding  `yaml:"merge,omitempty"`
	Normalize  *fileModuleBinding  `yaml:"normalize,omitempty"`
	Validators []fileModuleBinding `yaml:"validators,omitempty"`
	References map[string]string   `yaml:"references,omitempty"`
}

type FileConcurrencyConfig struct {
	TotalLLM     *int           `yaml:"total_llm,omitempty"`
	StageWorkers map[string]int `yaml:"stage_workers,omitempty"`
}

type FileDiagnosticsConfig struct {
	WorkDir   *string `yaml:"work_dir,omitempty"`
	Retention *string `yaml:"retention,omitempty"`
}

type FileWorkspaceConfig struct {
	Directory   *string                         `yaml:"directory,omitempty"`
	ChunkCache  *FileWorkspaceChunkCacheConfig  `yaml:"chunk_cache,omitempty"`
	Diagnostics *FileWorkspaceDiagnosticsConfig `yaml:"diagnostics,omitempty"`
	Resume      *FileWorkspaceEnabledConfig     `yaml:"resume,omitempty"`
	Debug       *FileWorkspaceEnabledConfig     `yaml:"debug,omitempty"`
}

type FileWorkspaceChunkCacheConfig struct {
	Mode      *string `yaml:"mode,omitempty"`
	Directory *string `yaml:"directory,omitempty"`
}

type FileWorkspaceDiagnosticsConfig struct {
	Enabled   *bool   `yaml:"enabled,omitempty"`
	Retention *string `yaml:"retention,omitempty"`
}

type FileWorkspaceEnabledConfig struct {
	Enabled *bool `yaml:"enabled,omitempty"`
}

type fileModuleBinding struct {
	Module     string
	LLMProfile string
	Retries    int
	Options    map[string]any
	References map[string]string
	Validators pipeline.ValidatorOverride
}

func (b *fileModuleBinding) UnmarshalYAML(node *yaml.Node) error {
	switch node.Kind {
	case yaml.ScalarNode:
		var module string
		if err := node.Decode(&module); err != nil {
			return fmt.Errorf("module binding must be a string or object")
		}
		b.Module = strings.TrimSpace(module)
		return nil
	case yaml.MappingNode:
		for i := 0; i < len(node.Content); i += 2 {
			keyNode := node.Content[i]
			valueNode := node.Content[i+1]
			switch keyNode.Value {
			case "module":
				var module string
				if err := valueNode.Decode(&module); err != nil {
					return err
				}
				b.Module = strings.TrimSpace(module)
			case "llm_profile":
				var llmProfile string
				if err := valueNode.Decode(&llmProfile); err != nil {
					return err
				}
				b.LLMProfile = strings.TrimSpace(llmProfile)
			case "retries":
				var retries int
				if err := valueNode.Decode(&retries); err != nil {
					return err
				}
				b.Retries = retries
			case "options":
				var options map[string]any
				if err := valueNode.Decode(&options); err != nil {
					return err
				}
				b.Options = normalizeOptions(options)
			case "references":
				var references map[string]string
				if err := valueNode.Decode(&references); err != nil {
					return err
				}
				b.References = references
			case "validators":
				b.Validators.Set = true
				var validators []fileModuleBinding
				if err := valueNode.Decode(&validators); err != nil {
					return err
				}
				b.Validators.Validators = make([]pipeline.ModuleBinding, len(validators))
				for i, validator := range validators {
					b.Validators.Validators[i] = validator.toPipelineBinding()
				}
			default:
				return fmt.Errorf("field %s not found in module binding", keyNode.Value)
			}
		}
		return nil
	default:
		return fmt.Errorf("module binding must be a string or object")
	}
}

func (b fileModuleBinding) toPipelineBinding() pipeline.ModuleBinding {
	return pipeline.ModuleBinding{
		Module:     strings.TrimSpace(b.Module),
		LLMProfile: strings.TrimSpace(b.LLMProfile),
		Retries:    b.Retries,
		Options:    cloneOptions(b.Options),
		References: normalizedStringMap(b.References),
		Validators: b.Validators,
	}
}

func LoadFileConfig(path string) (FileConfig, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return FileConfig{}, fmt.Errorf("read config file %q: %w", path, err)
	}
	cfg, err := ParseFileConfigYAML(data)
	if err != nil {
		return FileConfig{}, fmt.Errorf("parse config file %q: %w", path, err)
	}
	return cfg, nil
}

func ParseFileConfigYAML(data []byte) (FileConfig, error) {
	var fileCfg FileConfig
	decoder := yaml.NewDecoder(bytes.NewReader(data))
	decoder.KnownFields(true)
	if err := decoder.Decode(&fileCfg); err != nil {
		return FileConfig{}, fmt.Errorf("decode yaml: %w", err)
	}
	if fileCfg.Version == 0 {
		return FileConfig{}, fmt.Errorf("config version is required")
	}
	if fileCfg.Version != SupportedFileConfigVersion {
		return FileConfig{}, fmt.Errorf("unsupported config version %d", fileCfg.Version)
	}
	return fileCfg, nil
}

func (c *Config) ApplyFileConfig(fileCfg FileConfig) error {
	return c.applyFileConfigWithLookup(fileCfg, os.LookupEnv)
}

func (c *Config) ApplyFileConfigWithLookup(fileCfg FileConfig, lookup func(string) (string, bool)) error {
	return c.applyFileConfigWithLookup(fileCfg, lookup)
}

func (c *Config) applyFileConfigWithLookup(fileCfg FileConfig, lookup func(string) (string, bool)) error {
	_ = lookup
	if c == nil {
		return fmt.Errorf("config must not be nil")
	}
	if fileCfg.Version != SupportedFileConfigVersion {
		return fmt.Errorf("unsupported config version %d", fileCfg.Version)
	}
	if c.Pipelines == nil {
		c.Pipelines = map[string]pipeline.PipelineProfile{}
	}

	pipelineIDs, rawPipelineIDs, err := normalizedMapKeys(fileCfg.Pipelines, "pipeline id")
	if err != nil {
		return err
	}
	for _, pipelineID := range pipelineIDs {
		filePipeline := fileCfg.Pipelines[rawPipelineIDs[pipelineID]]
		if _, _, err := normalizedMapKeys(filePipeline.Artifacts, fmt.Sprintf("pipeline %q artifact lane id", pipelineID)); err != nil {
			return err
		}
		if _, _, err := normalizedMapKeys(filePipeline.References, fmt.Sprintf("pipeline %q reference slot", pipelineID)); err != nil {
			return err
		}
		if filePipeline.Chunk != nil {
			if _, _, err := normalizedMapKeys(filePipeline.Chunk.References, fmt.Sprintf("pipeline %q chunk reference slot", pipelineID)); err != nil {
				return err
			}
		}
		if _, _, err := normalizedMapKeys(filePipeline.Input.References, fmt.Sprintf("pipeline %q input reference slot", pipelineID)); err != nil {
			return err
		}
		if filePipeline.Output != nil {
			if _, _, err := normalizedMapKeys(filePipeline.Output.References, fmt.Sprintf("pipeline %q output reference slot", pipelineID)); err != nil {
				return err
			}
		}
		for rawLaneID, fileLane := range filePipeline.Artifacts {
			laneID := strings.TrimSpace(rawLaneID)
			if laneID == "" {
				continue
			}
			if _, _, err := normalizedMapKeys(fileLane.References, fmt.Sprintf("pipeline %q lane %q reference slot", pipelineID, laneID)); err != nil {
				return err
			}
			if _, _, err := normalizedMapKeys(fileLane.Extract.References, fmt.Sprintf("pipeline %q lane %q extract reference slot", pipelineID, laneID)); err != nil {
				return err
			}
			if fileLane.Merge != nil {
				if _, _, err := normalizedMapKeys(fileLane.Merge.References, fmt.Sprintf("pipeline %q lane %q merge reference slot", pipelineID, laneID)); err != nil {
					return err
				}
			}
			if fileLane.Normalize != nil {
				if _, _, err := normalizedMapKeys(fileLane.Normalize.References, fmt.Sprintf("pipeline %q lane %q normalize reference slot", pipelineID, laneID)); err != nil {
					return err
				}
			}
			for i, validator := range fileLane.Validators {
				if _, _, err := normalizedMapKeys(validator.References, fmt.Sprintf("pipeline %q lane %q validator[%d] reference slot", pipelineID, laneID, i)); err != nil {
					return err
				}
			}
		}
	}

	if fileCfg.Scriptorium != nil {
		if fileCfg.Scriptorium.ProfileDir != nil {
			value := strings.TrimSpace(*fileCfg.Scriptorium.ProfileDir)
			if value == "" {
				return fmt.Errorf("scriptorium.profile_dir must not be empty when set")
			}
			c.Scriptorium.ProfileDir = value
		}
		if fileCfg.Scriptorium.ProfileFile != nil {
			value := strings.TrimSpace(*fileCfg.Scriptorium.ProfileFile)
			if value == "" {
				return fmt.Errorf("scriptorium.profile_file must not be empty when set")
			}
			c.Scriptorium.ProfileFile = value
		}
	}

	for _, pipelineID := range pipelineIDs {
		filePipeline := fileCfg.Pipelines[rawPipelineIDs[pipelineID]]
		laneIDs, rawLaneIDs, err := normalizedMapKeys(filePipeline.Artifacts, fmt.Sprintf("pipeline %q artifact lane id", pipelineID))
		if err != nil {
			return err
		}
		profile := pipeline.PipelineProfile{
			ID:         pipelineID,
			Input:      filePipeline.Input.toPipelineBinding(),
			Artifacts:  make(map[string]pipeline.ArtifactLaneProfile, len(filePipeline.Artifacts)),
			References: normalizedStringMap(filePipeline.References),
		}
		if filePipeline.Chunk != nil {
			profile.Chunk = filePipeline.Chunk.toPipelineBinding()
		}
		if filePipeline.Output != nil {
			profile.Output = filePipeline.Output.toPipelineBinding()
		}
		for _, laneID := range laneIDs {
			fileLane := filePipeline.Artifacts[rawLaneIDs[laneID]]
			extract := fileLane.Extract.toPipelineBinding()
			extract.References = mergeStringMaps(normalizedStringMap(fileLane.References), extract.References)
			lane := pipeline.ArtifactLaneProfile{
				Extract:    extract,
				References: normalizedStringMap(fileLane.References),
			}
			if fileLane.Merge != nil {
				lane.Merge = fileLane.Merge.toPipelineBinding()
			}
			if fileLane.Normalize != nil {
				lane.Normalize = fileLane.Normalize.toPipelineBinding()
			}
			if len(fileLane.Validators) > 0 {
				lane.Validators = make([]pipeline.ModuleBinding, len(fileLane.Validators))
				for i, validator := range fileLane.Validators {
					lane.Validators[i] = validator.toPipelineBinding()
				}
			}
			profile.Artifacts[laneID] = lane
		}
		c.Pipelines[pipelineID] = profile
	}

	if fileCfg.Concurrency != nil && fileCfg.Concurrency.TotalLLM != nil {
		c.Concurrency.TotalLLM = *fileCfg.Concurrency.TotalLLM
	}
	if fileCfg.Concurrency != nil && fileCfg.Concurrency.StageWorkers != nil {
		workers, configured, err := normalizeStageWorkers(fileCfg.Concurrency.StageWorkers)
		if err != nil {
			return err
		}
		c.Concurrency.StageWorkers = workers
		c.Concurrency.extractWorkersConfigured = configured
	}
	c.Concurrency.recomputeStageWorkerDefaults()
	if fileCfg.Diagnostics != nil {
		if fileCfg.Diagnostics.WorkDir != nil {
			c.Diagnostics.WorkDir = strings.TrimSpace(*fileCfg.Diagnostics.WorkDir)
		}
		if fileCfg.Diagnostics.Retention != nil {
			c.Diagnostics.Retention = diagnostics.RetentionMode(strings.TrimSpace(*fileCfg.Diagnostics.Retention))
		}
	}
	if fileCfg.Workspace != nil {
		if fileCfg.Workspace.Directory != nil {
			c.Workspace.Directory = strings.TrimSpace(*fileCfg.Workspace.Directory)
		}
		if fileCfg.Workspace.ChunkCache != nil {
			if fileCfg.Workspace.ChunkCache.Mode != nil {
				mode, err := pipeline.ParseChunkCacheMode(*fileCfg.Workspace.ChunkCache.Mode)
				if err != nil {
					return fmt.Errorf("workspace.chunk_cache.mode: %w", err)
				}
				c.Workspace.ChunkCache.Mode = mode
			}
			if fileCfg.Workspace.ChunkCache.Directory != nil {
				c.Workspace.ChunkCache.Directory = cleanOptionalPath(*fileCfg.Workspace.ChunkCache.Directory)
			}
		}
		if fileCfg.Workspace.Diagnostics != nil {
			if fileCfg.Workspace.Diagnostics.Enabled != nil {
				c.Workspace.Diagnostics.Enabled = *fileCfg.Workspace.Diagnostics.Enabled
				c.Workspace.Diagnostics.enabledSet = true
			}
			if fileCfg.Workspace.Diagnostics.Retention != nil {
				c.Workspace.Diagnostics.Retention = diagnostics.RetentionMode(strings.TrimSpace(*fileCfg.Workspace.Diagnostics.Retention))
				c.Workspace.Diagnostics.retentionSet = true
			}
		}
		if fileCfg.Workspace.Resume != nil && fileCfg.Workspace.Resume.Enabled != nil {
			c.Workspace.Resume.Enabled = *fileCfg.Workspace.Resume.Enabled
		}
		if fileCfg.Workspace.Debug != nil && fileCfg.Workspace.Debug.Enabled != nil {
			c.Workspace.Debug.Enabled = *fileCfg.Workspace.Debug.Enabled
		}
	}
	c.RecomputeEffectiveDiagnostics()

	return nil
}

func cleanOptionalPath(value string) string {
	value = strings.TrimSpace(value)
	if value == "" {
		return ""
	}
	return filepath.Clean(value)
}

func normalizeStageWorkers(values map[string]int) (map[string]int, bool, error) {
	workers := make(map[string]int, len(values))
	configured := false
	for rawKey, value := range values {
		key := strings.TrimSpace(rawKey)
		if key == "" {
			return nil, false, fmt.Errorf("concurrency.stage_workers key must not be empty")
		}
		if key != "extract" {
			return nil, false, fmt.Errorf("concurrency.stage_workers key %q is not supported", rawKey)
		}
		if _, exists := workers[key]; exists {
			return nil, false, fmt.Errorf("concurrency.stage_workers key %q is duplicated after trimming", key)
		}
		workers[key] = value
		configured = true
	}
	return workers, configured, nil
}

func normalizedMapKeys[T any](values map[string]T, keyName string) ([]string, map[string]string, error) {
	keys := make([]string, 0, len(values))
	rawByNormalized := make(map[string]string, len(values))
	for rawID := range values {
		id := strings.TrimSpace(rawID)
		if id == "" {
			return nil, nil, fmt.Errorf("%s must not be empty", keyName)
		}
		if _, ok := rawByNormalized[id]; ok {
			return nil, nil, fmt.Errorf("%s %q is duplicated after trimming", keyName, id)
		}
		rawByNormalized[id] = rawID
		keys = append(keys, id)
	}
	sort.Strings(keys)
	return keys, rawByNormalized, nil
}

func normalizedStringMap(values map[string]string) map[string]string {
	if len(values) == 0 {
		return nil
	}
	out := make(map[string]string, len(values))
	keys := make([]string, 0, len(values))
	rawByNormalized := make(map[string]string, len(values))
	for rawKey := range values {
		key := strings.TrimSpace(rawKey)
		rawByNormalized[key] = rawKey
		keys = append(keys, key)
	}
	sort.Strings(keys)
	for _, key := range keys {
		out[key] = strings.TrimSpace(values[rawByNormalized[key]])
	}
	return out
}

func mergeStringMaps(base map[string]string, override map[string]string) map[string]string {
	if len(base) == 0 && len(override) == 0 {
		return nil
	}
	out := make(map[string]string, len(base)+len(override))
	for key, value := range base {
		out[key] = value
	}
	for key, value := range override {
		out[key] = value
	}
	return out
}

func normalizeOptions(options map[string]any) map[string]any {
	if len(options) == 0 {
		return nil
	}
	return cloneOptions(options)
}