package preparation

import (
	"bytes"
	"encoding/json"
	"io"
	"regexp"
	"strconv"
	"strings"

	"github.com/aritmolab/thothii/tools/tht/internal/authconfig"
	"github.com/aritmolab/thothii/tools/tht/internal/config"
	"github.com/aritmolab/thothii/tools/tht/internal/safeio"
	"gopkg.in/yaml.v3"
)

type Issue struct {
	Document   string `json:"document"`
	Field      string `json:"field"`
	Code       string `json:"code"`
	Correction string `json:"correction"`
}
type Report struct {
	SchemaVersion  int      `json:"schema_version"`
	Scope          string   `json:"scope"`
	OK             bool     `json:"ok"`
	Issues         []Issue  `json:"issues"`
	Warnings       []string `json:"warnings"`
	DeferredChecks []string `json:"deferred_checks"`
}

func NewReport() Report {
	return Report{SchemaVersion: 1, Scope: "application-documents", Issues: []Issue{}, Warnings: []string{}, DeferredChecks: []string{"release-assets", "external-connectivity", "catalog-import", "runtime-readiness"}}
}
func (r *Report) Add(document, field, code, correction string) {
	r.OK = false
	r.Issues = append(r.Issues, Issue{document, field, code, correction})
}
func placeholder(value string) bool {
	upper := strings.ToUpper(value)
	return strings.Contains(upper, "CHANGE_ME") || strings.Contains(upper, "REPLACE_ME") || strings.Contains(upper, "YOUR_API_KEY") || strings.Contains(upper, "<PASSWORD>")
}

// CheckYAML refuses unresolved placeholders and ambiguous authored YAML without returning values.
func CheckYAML(path, document string, report *Report) bool {
	content, err := safeio.ReadCanonicalPrivateRegular(path, 1<<20)
	if err != nil {
		report.Add(document, "$", "file_unavailable", "Use a readable, private regular document at a canonical absolute path (no links).")
		return false
	}
	decoder := yaml.NewDecoder(bytes.NewReader(content))
	var node, extra yaml.Node
	if err := decoder.Decode(&node); err != nil || decoder.Decode(&extra) != io.EOF {
		report.Add(document, "$", "yaml_invalid", "Keep one well-formed YAML document.")
		return false
	}
	var walk func(*yaml.Node) bool
	walk = func(n *yaml.Node) bool {
		if n.Kind == yaml.AliasNode || n.Tag == "!!merge" {
			return false
		}
		if n.Kind == yaml.ScalarNode && placeholder(n.Value) {
			return false
		}
		if n.Kind == yaml.MappingNode {
			seen := map[string]bool{}
			for index := 0; index < len(n.Content); index += 2 {
				key := n.Content[index]
				if key.Kind != yaml.ScalarNode || seen[key.Value] {
					return false
				}
				seen[key.Value] = true
			}
		}
		for _, child := range n.Content {
			if !walk(child) {
				return false
			}
		}
		return true
	}
	if !walk(&node) {
		report.Add(document, "$", "incomplete_or_ambiguous", "Replace CHANGE_ME/REPLACE_ME placeholders, remove duplicate keys, aliases and YAML merge keys.")
		return false
	}
	return true
}

var environmentKey = regexp.MustCompile(`^[A-Z][A-Z0-9_]*$`)

func checkEnvironment(path string, report *Report) bool {
	contents, err := safeio.ReadCanonicalPrivateRegular(path, 1<<20)
	if err != nil {
		report.Add("operator.env", "$", "environment_unavailable", "Provide a private readable environment file.")
		return false
	}
	seen := map[string]bool{}
	for _, raw := range strings.Split(string(contents), "\n") {
		line := strings.TrimSpace(raw)
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		key, value, found := strings.Cut(line, "=")
		if !found || !environmentKey.MatchString(key) || seen[key] || placeholder(value) || strings.Contains(value, "$") {
			report.Add("operator.env", "$", "environment_invalid", "Use one literal KEY=value per line, unique uppercase keys, and replace placeholders; shell interpolation is not accepted.")
			return false
		}
		if strings.HasSuffix(key, "_PASSWORD") || strings.HasSuffix(key, "_API_KEY") {
			report.Add("operator.env", "$", "inline_secret", "Move credential values to protected files and keep only file references in operator.env.")
			return false
		}
		seen[key] = true
	}
	return true
}

func CheckSecret(path, document, field string, allowEmpty bool, report *Report) bool {
	contents, err := safeio.ReadCanonicalPrivateRegular(path, 64<<10)
	if err != nil || (!allowEmpty && len(bytes.TrimSpace(contents)) == 0) || placeholder(string(contents)) {
		report.Add(document, field, "secret_unavailable", "Supply a non-placeholder private readable regular secret file (owner-only permissions, no links); do not put its contents in YAML or logs.")
		return false
	}
	return true
}

func Validate(path string) (config.Installation, Report) {
	report := NewReport()
	if !CheckYAML(path, "thothii-installation.yaml", &report) {
		return config.Installation{}, report
	}
	// Read only the location before the canonical loader checks every field.
	contents, _ := safeio.ReadCanonicalPrivateRegular(path, 1<<20)
	var location struct {
		EnvFile string `yaml:"envFile"`
	}
	if yaml.Unmarshal(contents, &location) != nil {
		report.Add("thothii-installation.yaml", "envFile", "schema_invalid", "Set envFile to one absolute path string, then correct the remaining descriptor fields.")
		return config.Installation{}, report
	}
	if !checkEnvironment(location.EnvFile, &report) {
		return config.Installation{}, report
	}
	installation, err := config.LoadPrepared(path)
	if err != nil {
		field, correction := "$", "Check installation schema v2, absolute paths, workspace remote/branch and matching environment values. Custom overrides and Git credential/CA files must exist."
		if strings.Contains(err.Error(), "modelCatalog") {
			field, correction = "modelCatalog", "Check interaction default eligibility, provider endpoints/authentication, embedding id/dimensions, and the private provider key bundle."
		}
		if strings.Contains(err.Error(), "authentication") {
			field, correction = "authentication", "Match the authentication directory to operator.env and prepare its protected files."
		}
		report.Add("thothii-installation.yaml", field, "configuration_invalid", correction)
		return config.Installation{}, report
	}
	value := func(key string) string { result, _ := installation.EnvironmentValue(key); return result }
	for _, key := range []string{"COMPOSE_PROJECT_NAME", "THT_WORKSPACE_INSTALLATION_ID", "THT_INSTALLATION_CONFIG_SOURCE", "THT_SECRETS_FILE", "PI_AUTH_FILE", "THT_CATALOG_RUNTIME_PASSWORD_SOURCE", "THT_CATALOG_MIGRATOR_PASSWORD_SOURCE"} {
		if value(key) == "" {
			report.Add("operator.env", key, "required", "Supply this installation parameter or protected file reference before setup.")
		}
	}
	if value("THT_INSTALLATION_CONFIG_SOURCE") != path {
		report.Add("operator.env", "THT_INSTALLATION_CONFIG_SOURCE", "path_mismatch", "Point to the exact installation descriptor being validated.")
	}
	for _, key := range []string{"THOTH_HTTP_PORT", "THOTH_CORE_HTTP_PORT", "MAX_PI_PROCESSES"} {
		number, err := strconv.Atoi(value(key))
		if err != nil || number < 1 || number > 65535 {
			report.Add("operator.env", key, "invalid_number", "Supply a positive integer; HTTP ports must be within 1..65535.")
		}
	}
	if value("THOTH_HTTP_PORT") == value("THOTH_CORE_HTTP_PORT") {
		report.Add("operator.env", "THOTH_CORE_HTTP_PORT", "port_collision", "Choose different frontend and core host ports.")
	}
	files, err := installation.SecretFiles()
	if err != nil {
		report.Add("operator.env", "$", "secret_references_invalid", "Use canonical absolute paths for all _FILE and _SOURCE references.")
	}
	for _, file := range files {
		// The descriptor is a _SOURCE reference too, but its YAML values were already checked.
		// Template instructions in comments are not unresolved credential placeholders.
		if file == path {
			continue
		}
		allowEmpty := file == value("THT_WORKSPACE_GIT_CREDENTIALS_FILE")
		CheckSecret(file, "operator.env", "protected-file-reference", allowEmpty, &report)
	}
	auth, users, err := authconfig.Load(installation.AuthenticationDirectory())
	if err != nil {
		report.Add("auth/auth.yaml", "$", "authentication_invalid", "Prepare and validate local authentication documents before setup, including the initial administrator.")
	} else if auth.Mode == "local" {
		admin := false
		for _, user := range users.Users {
			for _, role := range user.Roles {
				if user.Enabled && role == authconfig.RoleAdmin {
					admin = true
				}
			}
		}
		if !admin {
			report.Add("auth/users.yaml", "users", "administrator_missing", "Enable at least one administrator before setup.")
		}
	} else {
		report.Add("auth/auth.yaml", "mode", "unsupported_bootstrap", "This preparation increment supports local administrative authentication; use the documented existing OIDC preparation path until its offline bootstrap validation is available.")
	}
	checkPiCredentials(value("PI_AUTH_FILE"), installation.ModelCatalog, &report)
	report.OK = len(report.Issues) == 0
	return installation, report
}

// Pi stores api_key or oauth records. Require literal prepared material here; model
// environment references belong to the catalog's secret_env path, not host process state.
func checkPiCredentials(path string, catalog config.ModelCatalog, report *Report) {
	contents, err := safeio.ReadCanonicalPrivateRegular(path, 64<<10)
	var credentials map[string]map[string]any
	invalid := err != nil || json.Unmarshal(contents, &credentials) != nil || credentials == nil
	literal := func(value any) bool {
		text, ok := value.(string)
		return ok && strings.TrimSpace(text) != "" && !strings.HasPrefix(text, "!") && !strings.Contains(text, "$") && !placeholder(text)
	}
	var declarative func(any) bool
	declarative = func(value any) bool {
		switch v := value.(type) {
		case string:
			return !strings.HasPrefix(v, "!")
		case []any:
			for _, item := range v {
				if !declarative(item) {
					return false
				}
			}
		case map[string]any:
			for _, item := range v {
				if !declarative(item) {
					return false
				}
			}
		}
		return true
	}
	seen := map[string]bool{}
	for provider, record := range credentials {
		name := strings.ToLower(strings.TrimSpace(provider))
		if name == "" || provider != name || seen[name] || !declarative(record) {
			invalid = true
		}
		seen[name] = true
		switch record["type"] {
		case "api_key":
			if !literal(record["key"]) {
				invalid = true
			}
			if env, present := record["env"]; present {
				values, ok := env.(map[string]any)
				if !ok {
					invalid = true
				}
				for _, value := range values {
					if _, ok := value.(string); !ok {
						invalid = true
					}
				}
			}
		case "oauth":
			expires, ok := record["expires"].(float64)
			if !literal(record["access"]) || !literal(record["refresh"]) || !ok || expires <= 0 {
				invalid = true
			}
		default:
			invalid = true
		}
	}
	for id, provider := range catalog.Providers {
		if provider.Authentication.Mode == "pi_auth" && !seen[id] {
			invalid = true
		}
	}
	if invalid {
		report.Add("pi-auth.json", "providers", "provider_auth_invalid", "Provide a JSON object with literal api_key/type+key or oauth/type+access+refresh+expires records for selected Pi providers; use catalog secret_env for environment-based keys. Commands and unresolved references are not accepted.")
	}
}