package config

import (
	"fmt"
	"strings"
	"time"

	"gitea.maximumdirect.net/eric/audita/v3/internal/core/modulecatalog"
	"gitea.maximumdirect.net/eric/audita/v3/internal/core/outputschema"
	ck "go.maximumdirect.net/configkit"
)

const (
	DefaultTranscriptDescriptionMaxChars = 500
	DefaultValidationMaxPromptTokens     = 2048
)

// Config contains application settings. Invocation paths are not settings.
type Config struct {
	Version             int                           `yaml:"version"`
	Glossaries          []string                      `yaml:"glossaries"`
	ProtectedTerms      []string                      `yaml:"protected_terms"`
	GlossaryCollections map[string]GlossaryCollection `yaml:"glossary_collections"`
	LLM                 LLM                           `yaml:"llm"`
	Pipeline            Pipeline                      `yaml:"pipeline"`
	Output              Output                        `yaml:"output"`
	Validation          Validation                    `yaml:"validation"`
	Chunking            Chunking                      `yaml:"chunking"`
	Normalization       Normalization                 `yaml:"normalization"`
	Thresholds          Thresholds                    `yaml:"thresholds"`
	Context             Context                       `yaml:"context"`
	Reporting           Reporting                     `yaml:"reporting"`
	Diagnostics         Diagnostics                   `yaml:"diagnostics"`
}

type GlossaryCollection struct {
	Entries []GlossaryEntry `yaml:"entries"`
}
type GlossaryEntry struct {
	ID          string         `yaml:"id"`
	Name        string         `yaml:"name"`
	Category    string         `yaml:"category"`
	Description string         `yaml:"description"`
	Aliases     []string       `yaml:"aliases"`
	Plural      *string        `yaml:"plural"`
	Extra       map[string]any `yaml:",inline"`
}
type LLM struct {
	ProposalProfile   *string       `yaml:"proposal_profile"`
	ValidationProfile *string       `yaml:"validation_profile"`
	TransientRetries  int           `yaml:"transient_retries"`
	RepairAttempts    int           `yaml:"repair_attempts"`
	OperationTimeout  time.Duration `yaml:"operation_timeout"`
}
type Pipeline struct {
	Stages []Stage `yaml:"stages"`
}
type Stage struct {
	Module              string     `yaml:"module"`
	ID                  *string    `yaml:"id"`
	Glossaries          []string   `yaml:"glossaries"`
	ProtectedTerms      []string   `yaml:"protected_terms"`
	ConfidenceThreshold float64    `yaml:"confidence_threshold"`
	LLM                 LLM        `yaml:"llm"`
	Validation          Validation `yaml:"validation"`
	Context             Context    `yaml:"context"`
}
type Output struct {
	Schema string `yaml:"schema"`
}
type Validation struct {
	MaxPromptTokens int `yaml:"max_prompt_tokens"`
}
type Chunking struct {
	TargetSections   *int `yaml:"target_sections"`
	MaxSectionTokens int  `yaml:"max_section_tokens"`
	MinSectionTokens int  `yaml:"min_section_tokens"`
}
type Normalization struct {
	MaxSegmentGap      float64 `yaml:"max_segment_gap"`
	EllipsisGap        float64 `yaml:"ellipsis_gap"`
	MaxSegmentDuration float64 `yaml:"max_segment_duration"`
	MaxSegmentTokens   int     `yaml:"max_segment_tokens"`
}
type Thresholds struct {
	Glossary   float64 `yaml:"glossary"`
	Homophones float64 `yaml:"homophones"`
	SpokenWord float64 `yaml:"spoken_word"`
	Grammar    float64 `yaml:"grammar"`
}
type Context struct {
	Description string `yaml:"description"`
}
type Diagnostics struct {
	WorkDir string `yaml:"work_dir"`
}
type Reporting struct {
	Enabled   bool   `yaml:"enabled"`
	StdoutDir string `yaml:"stdout_dir"`
}

func defaults() Config {
	return Config{
		Version:       3,
		LLM:           LLM{TransientRetries: 2, RepairAttempts: 2, OperationTimeout: 15 * time.Minute},
		Pipeline:      Pipeline{Stages: []Stage{{Module: "glossary"}, {Module: "homophones"}, {Module: "glossary"}, {Module: "spoken_word"}, {Module: "grammar"}}},
		Output:        Output{Schema: "bare-segments"},
		Validation:    Validation{MaxPromptTokens: DefaultValidationMaxPromptTokens},
		Chunking:      Chunking{MaxSectionTokens: 8192, MinSectionTokens: 2048},
		Normalization: Normalization{MaxSegmentGap: 4, EllipsisGap: 3.5, MaxSegmentDuration: 60, MaxSegmentTokens: 2048},
		Thresholds:    Thresholds{Glossary: .8, Homophones: .8, SpokenWord: .8, Grammar: .8},
		Reporting:     Reporting{Enabled: true, StdoutDir: "."},
		Diagnostics:   Diagnostics{WorkDir: "/tmp/audita"},
	}
}

const glossaryImports = `config:
  imports:
    - path: glossary.yml
      required: false
      destination: [glossary_collections]
    - dir: glossary
      required: false
      recursive: true
      pattern: ["*.yml", "*.yaml"]
      destination: [glossary_collections]
`

// Load resolves the selected main source and preserves native source evidence.
func Load(input ck.Input, overlay string, overrides ...ck.Override) (*ck.Result[Config], error) {
	input.Imports = true
	return ck.LoadLayered(input, ck.LayeredOptions[Config]{
		Overlay: overlay, Overrides: overrides,
		Underlays: []ck.Underlay{{Inputs: []ck.Input{{Source: ck.Bytes("Audita glossary imports", []byte(glossaryImports)), Imports: true, MainRelative: ck.MainRelative()}}}},
		Definition: ck.Definition[Config]{
			Defaults:           defaults,
			SequenceIdentities: []ck.SequenceIdentity{ck.SequenceIdentityMatching(ck.SequenceSelector{ck.SequenceLiteralKey("glossary_collections"), ck.SequenceAnyMappingKey(), ck.SequenceLiteralKey("entries")}, "id")},
			Version: &ck.VersionRule{Path: ck.Keys("version"), Check: func(version ck.Version, v *ck.Validation) error {
				if version.Present && (version.Null || version.Text != "3") {
					v.Error(ck.Keys("version"), "use application configuration version 3; see docs/migrations/v3.md")
				}
				return nil
			}},
			Resolve:  resolveSettings,
			Validate: validate,
		},
	})
}

func validate(c *Config, v *ck.Validation) {
	check := func(ok bool, path ck.Path, message string) {
		if !ok {
			v.Error(path, message)
		}
	}
	for name, collection := range c.GlossaryCollections {
		for i, entry := range collection.Entries {
			path := ck.Keys("glossary_collections", name, "entries").Index(i)
			check(entry.ID != "", path.Key("id"), "entry id must not be empty")
			check(entry.Name != "", path.Key("name"), "entry name must not be empty")
			check(entry.Category != "", path.Key("category"), "entry category must not be empty")
			for index, alias := range entry.Aliases {
				check(alias != "", path.Key("aliases").Index(index), "alias must not be empty")
			}
			check(entry.Plural == nil || *entry.Plural != "", path.Key("plural"), "plural must not be empty")
		}
	}
	check(c.LLM.TransientRetries >= 0, ck.Keys("llm", "transient_retries"), "retry budget must be non-negative")
	check(c.LLM.RepairAttempts >= 0 && c.LLM.RepairAttempts <= 3, ck.Keys("llm", "repair_attempts"), "repair attempts must be between zero and three")
	check(c.LLM.OperationTimeout > 0, ck.Keys("llm", "operation_timeout"), "operation timeout must be positive")
	check(c.LLM.ValidationProfile == nil || *c.LLM.ValidationProfile != "", ck.Keys("llm", "validation_profile"), "validation profile must not be empty; use null to clear it")
	validateSelections := func(values []string, path ck.Path) {
		for i, name := range values {
			_, exists := c.GlossaryCollections[name]
			check(exists, path.Index(i), "unknown glossary collection")
		}
	}
	validateSelections(c.Glossaries, ck.Keys("glossaries"))
	validateSelections(c.ProtectedTerms, ck.Keys("protected_terms"))
	ids := make(map[string]bool)
	for i, item := range c.Pipeline.Stages {
		path := ck.Keys("pipeline", "stages").Index(i)
		check(modulecatalog.IsSupported(item.Module), path.Key("module"), "unsupported module key")
		if item.ID != nil {
			check(*item.ID != "", path.Key("id"), "id must not be empty")
			check(!ids[*item.ID], path.Key("id"), "id must be unique")
			ids[*item.ID] = true
		}
		validateSelections(item.Glossaries, path.Key("glossaries"))
		validateSelections(item.ProtectedTerms, path.Key("protected_terms"))
		check(item.ConfidenceThreshold >= 0 && item.ConfidenceThreshold <= 1, path.Key("confidence_threshold"), "confidence threshold must be between zero and one")
		check(item.LLM.ValidationProfile == nil || *item.LLM.ValidationProfile != "", path.Key("llm").Key("validation_profile"), "validation profile must not be empty; use null to clear it")
		check(item.LLM.TransientRetries >= 0, path.Key("llm").Key("transient_retries"), "retry budget must be non-negative")
		check(item.LLM.RepairAttempts >= 0 && item.LLM.RepairAttempts <= 3, path.Key("llm").Key("repair_attempts"), "repair attempts must be between zero and three")
		check(item.LLM.OperationTimeout > 0, path.Key("llm").Key("operation_timeout"), "operation timeout must be positive")
		check(item.Validation.MaxPromptTokens > 0, path.Key("validation").Key("max_prompt_tokens"), "validation prompt budget must be positive")
		check(len(strings.TrimSpace(item.Context.Description)) <= DefaultTranscriptDescriptionMaxChars, path.Key("context").Key("description"), fmt.Sprintf("description must be at most %d bytes after trimming", DefaultTranscriptDescriptionMaxChars))
	}
	check(outputschema.IsSupported(c.Output.Schema), ck.Keys("output", "schema"), "unsupported output schema")
	check(c.Validation.MaxPromptTokens > 0, ck.Keys("validation", "max_prompt_tokens"), "validation prompt budget must be positive")
	check(c.Chunking.MaxSectionTokens > 0, ck.Keys("chunking", "max_section_tokens"), "maximum section tokens must be positive")
	check(c.Chunking.MinSectionTokens > 0 && c.Chunking.MinSectionTokens <= c.Chunking.MaxSectionTokens, ck.Keys("chunking", "min_section_tokens"), "minimum section tokens must be positive and no greater than maximum")
	check(c.Chunking.TargetSections == nil || *c.Chunking.TargetSections > 0, ck.Keys("chunking", "target_sections"), "target sections must be positive when set")
	check(c.Normalization.MaxSegmentGap >= 0, ck.Keys("normalization", "max_segment_gap"), "maximum segment gap must be non-negative")
	check(c.Normalization.EllipsisGap >= 0, ck.Keys("normalization", "ellipsis_gap"), "ellipsis gap must be non-negative")
	check(c.Normalization.MaxSegmentDuration > 0, ck.Keys("normalization", "max_segment_duration"), "maximum segment duration must be positive")
	check(c.Normalization.MaxSegmentTokens > 0, ck.Keys("normalization", "max_segment_tokens"), "maximum segment tokens must be positive")
	for name, threshold := range map[string]float64{"glossary": c.Thresholds.Glossary, "homophones": c.Thresholds.Homophones, "spoken_word": c.Thresholds.SpokenWord, "grammar": c.Thresholds.Grammar} {
		check(threshold >= 0 && threshold <= 1, ck.Keys("thresholds", name), "confidence threshold must be between zero and one")
	}
	check(len(strings.TrimSpace(c.Context.Description)) <= DefaultTranscriptDescriptionMaxChars, ck.Keys("context", "description"), fmt.Sprintf("description must be at most %d bytes after trimming", DefaultTranscriptDescriptionMaxChars))
}