package config

import (
	"fmt"
	"strings"
	"time"

	ck "gitea.maximumdirect.net/eric/ConfigKit"
	"gitea.maximumdirect.net/eric/audita/internal/core/modulecatalog"
	"gitea.maximumdirect.net/eric/audita/internal/core/outputschema"
)

const (
	DefaultModulesCSV                    = "glossary,homophones,glossary,spoken_word,grammar"
	DefaultTranscriptDescriptionMaxChars = 500
	DefaultValidationMaxPromptTokens     = 2048
)

// Config is the version-2 application configuration. Invocation paths are not settings.
type Config struct {
	Version       int                `yaml:"version"`
	ProfilesDir   string             `yaml:"profiles_dir"`
	Backends      map[string]Backend `yaml:"backends"`
	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 Backend struct {
	Endpoint      string     `yaml:"endpoint"`
	Concurrency   int        `yaml:"concurrency"`
	QueueCapacity int        `yaml:"queue_capacity"`
	Credential    *ck.Secret `yaml:"credential"`
}
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 {
	Modules []string `yaml:"modules"`
}
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 {
	Debug   bool   `yaml:"debug"`
	WorkDir string `yaml:"work_dir"`
}
type Reporting struct {
	Enabled   bool   `yaml:"enabled"`
	StdoutDir string `yaml:"stdout_dir"`
}

func defaults() Config {
	return Config{
		ProfilesDir:   "profiles",
		LLM:           LLM{TransientRetries: 2, RepairAttempts: 2, OperationTimeout: 15 * time.Minute},
		Pipeline:      Pipeline{Modules: []string{"glossary", "homophones", "glossary", "spoken_word", "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"},
	}
}

// Load resolves the selected main file, optional overlay, and explicit setting overrides.
// Its result retains safe effective output and provenance for CLI composition.
func Load(source ck.Source, overlay string, overrides ...ck.Override) (*ck.Result[Config], error) {
	return ck.Load(source, ck.Options[Config]{
		Overlay: overlay, Overrides: overrides,
		Definition: ck.Definition[Config]{
			Defaults: defaults,
			Version: &ck.VersionRule{Path: ck.Keys("version"), Check: func(version ck.Version, v *ck.Validation) error {
				if !version.Present || version.Null || version.Text != "2" {
					v.Error(ck.Keys("version"), "version 2 is required; see docs/migrations/v2.md")
				}
				return nil
			}},
			Resolve: func(c *Config, r *ck.Resolution) error {
				ck.Default(r, ck.Keys("llm", "validation_profile"), &c.LLM.ValidationProfile, c.LLM.ProposalProfile, "validation uses the final proposal profile when omitted", ck.Keys("llm", "proposal_profile"))
				for id, backend := range c.Backends {
					changed := false
					if !r.IsExplicit(ck.Keys("backends", id, "concurrency")) {
						backend.Concurrency = 1
						changed = true
					}
					if !r.IsExplicit(ck.Keys("backends", id, "queue_capacity")) {
						backend.QueueCapacity = 1024
						changed = true
					}
					if changed {
						c.Backends[id] = backend
						r.Record(ck.Keys("backends", id), ck.ChangeDerivedDefault, "finite backend defaults")
					}
				}
				return nil
			},
			Validate: validate,
		},
	})
}

func validate(c *Config, v *ck.Validation) {
	check := func(ok bool, path ck.Path, message string) {
		if !ok {
			v.Error(path, message)
		}
	}
	check(strings.TrimSpace(c.ProfilesDir) != "", ck.Keys("profiles_dir"), "profile directory is required")
	check(strings.TrimSpace(c.LLM.ProposalProfile) != "", ck.Keys("llm", "proposal_profile"), "proposal profile is required")
	check(strings.TrimSpace(c.LLM.ValidationProfile) != "", ck.Keys("llm", "validation_profile"), "validation profile is required")
	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(len(c.Backends) > 0, ck.Keys("backends"), "at least one backend is required")
	for id, b := range c.Backends {
		p := ck.Keys("backends", id)
		check(strings.TrimSpace(b.Endpoint) != "", p.Key("endpoint"), "backend endpoint is required")
		check(b.Concurrency > 0, p.Key("concurrency"), "backend concurrency must be positive")
		check(b.QueueCapacity >= 0, p.Key("queue_capacity"), "queue capacity must be non-negative")
	}
	for i, module := range c.Pipeline.Modules {
		check(modulecatalog.IsSupported(module), ck.Keys("pipeline", "modules").Index(i), "unsupported module key")
	}
	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))
}

// ParseModulesCSV is used only for an explicitly supplied --modules override.
func ParseModulesCSV(raw string) ([]string, error) {
	if raw == "" {
		return []string{}, nil
	}
	parts := strings.Split(raw, ",")
	for i := range parts {
		parts[i] = strings.TrimSpace(parts[i])
		if parts[i] == "" {
			return nil, fmt.Errorf("modules list contains an empty value")
		}
	}
	return parts, nil
}